feat(vm): Add boojum integration folder

core/lib/multivm/src/versions/vm_boojum_integration/README.md

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+# VM Crate
+
+This crate contains code that interacts with the VM (Virtual Machine). The VM itself is in a separate repository
+[era-zk_evm][zk_evm_repo_ext].
+
+## VM Dependencies
+
+The VM relies on several subcomponents or traits, such as Memory and Storage. These traits are defined in the `zk_evm`
+repository, while their implementations can be found in this crate, such as the storage implementation in
+`oracles/storage.rs` and the Memory implementation in `memory.rs`.
+
+Many of these implementations also support easy rollbacks and history, which is useful when creating a block with
+multiple transactions and needing to return the VM to a previous state if a transaction doesn't fit.
+
+## Running the VM
+
+To interact with the VM, you must initialize it with `L1BatchEnv`, which represents the initial parameters of the batch,
+`SystemEnv`, that represents the system parameters, and a reference to the Storage. To execute a transaction, you have
+to push the transaction into the bootloader memory and call the `execute_next_transaction` method.
+
+### Tracers
+
+The VM implementation allows for the addition of `Tracers`, which are activated before and after each instruction. This
+provides a more in-depth look into the VM, collecting detailed debugging information and logs. More details can be found
+in the `tracer/` directory.
+
+This VM also supports custom tracers. You can call the `inspect_next_transaction` method with a custom tracer and
+receive the result of the execution.
+
+### Bootloader
+
+In the context of zkEVM, we usually think about transactions. However, from the VM's perspective, it runs a single
+program called the bootloader, which internally processes multiple transactions.
+
+### Rollbacks
+
+The `VMInstance` in `vm.rs` allows for easy rollbacks. You can save the current state at any moment by calling
+`make_snapshot()` and return to that state using `rollback_to_the_latest_snapshot()`.
+
+This rollback affects all subcomponents, such as memory, storage, and events, and is mainly used if a transaction
+doesn't fit in a block.
+
+[zk_evm_repo]: https://github.com/matter-labs/zk_evm 'internal zk EVM repo'
+[zk_evm_repo_ext]: https://github.com/matter-labs/era-zk_evm 'external zk EVM repo'

core/lib/multivm/src/versions/vm_boojum_integration/bootloader_state/l2_block.rs

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+use std::cmp::Ordering;
+
+use zksync_types::{MiniblockNumber, H256};
+use zksync_utils::concat_and_hash;
+
+use crate::{
+    interface::{L2Block, L2BlockEnv},
+    vm_latest::{
+        bootloader_state::{snapshot::L2BlockSnapshot, tx::BootloaderTx},
+        utils::l2_blocks::l2_block_hash,
+    },
+};
+
+const EMPTY_TXS_ROLLING_HASH: H256 = H256::zero();
+
+#[derive(Debug, Clone)]
+pub(crate) struct BootloaderL2Block {
+    pub(crate) number: u32,
+    pub(crate) timestamp: u64,
+    pub(crate) txs_rolling_hash: H256, // The rolling hash of all the transactions in the miniblock
+    pub(crate) prev_block_hash: H256,
+    // Number of the first l2 block tx in l1 batch
+    pub(crate) first_tx_index: usize,
+    pub(crate) max_virtual_blocks_to_create: u32,
+    pub(super) txs: Vec<BootloaderTx>,
+}
+
+impl BootloaderL2Block {
+    pub(crate) fn new(l2_block: L2BlockEnv, first_tx_place: usize) -> Self {
+        Self {
+            number: l2_block.number,
+            timestamp: l2_block.timestamp,
+            txs_rolling_hash: EMPTY_TXS_ROLLING_HASH,
+            prev_block_hash: l2_block.prev_block_hash,
+            first_tx_index: first_tx_place,
+            max_virtual_blocks_to_create: l2_block.max_virtual_blocks_to_create,
+            txs: vec![],
+        }
+    }
+
+    pub(super) fn push_tx(&mut self, tx: BootloaderTx) {
+        self.update_rolling_hash(tx.hash);
+        self.txs.push(tx)
+    }
+
+    pub(crate) fn get_hash(&self) -> H256 {
+        l2_block_hash(
+            MiniblockNumber(self.number),
+            self.timestamp,
+            self.prev_block_hash,
+            self.txs_rolling_hash,
+        )
+    }
+
+    fn update_rolling_hash(&mut self, tx_hash: H256) {
+        self.txs_rolling_hash = concat_and_hash(self.txs_rolling_hash, tx_hash)
+    }
+
+    pub(crate) fn interim_version(&self) -> BootloaderL2Block {
+        let mut interim = self.clone();
+        interim.max_virtual_blocks_to_create = 0;
+        interim
+    }
+
+    pub(crate) fn make_snapshot(&self) -> L2BlockSnapshot {
+        L2BlockSnapshot {
+            txs_rolling_hash: self.txs_rolling_hash,
+            txs_len: self.txs.len(),
+        }
+    }
+
+    pub(crate) fn apply_snapshot(&mut self, snapshot: L2BlockSnapshot) {
+        self.txs_rolling_hash = snapshot.txs_rolling_hash;
+        match self.txs.len().cmp(&snapshot.txs_len) {
+            Ordering::Greater => self.txs.truncate(snapshot.txs_len),
+            Ordering::Less => panic!("Applying snapshot from future is not supported"),
+            Ordering::Equal => {}
+        }
+    }
+    pub(crate) fn l2_block(&self) -> L2Block {
+        L2Block {
+            number: self.number,
+            timestamp: self.timestamp,
+            hash: self.get_hash(),
+        }
+    }
+}

core/lib/multivm/src/versions/vm_boojum_integration/bootloader_state/mod.rs

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+mod l2_block;
+mod snapshot;
+mod state;
+mod tx;
+
+pub(crate) mod utils;
+pub(crate) use snapshot::BootloaderStateSnapshot;
+pub use state::BootloaderState;

core/lib/multivm/src/versions/vm_boojum_integration/bootloader_state/snapshot.rs

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+use zksync_types::H256;
+
+#[derive(Debug, Clone)]
+pub(crate) struct BootloaderStateSnapshot {
+    /// ID of the next transaction to be executed.
+    pub(crate) tx_to_execute: usize,
+    /// Stored L2 blocks in bootloader memory
+    pub(crate) l2_blocks_len: usize,
+    /// Snapshot of the last L2 block. Only this block could be changed during the rollback
+    pub(crate) last_l2_block: L2BlockSnapshot,
+    /// The number of 32-byte words spent on the already included compressed bytecodes.
+    pub(crate) compressed_bytecodes_encoding: usize,
+    /// Current offset of the free space in the bootloader memory.
+    pub(crate) free_tx_offset: usize,
+    /// Whether the pubdata information has been provided already
+    pub(crate) is_pubdata_information_provided: bool,
+}
+
+#[derive(Debug, Clone)]
+pub(crate) struct L2BlockSnapshot {
+    /// The rolling hash of all the transactions in the miniblock
+    pub(crate) txs_rolling_hash: H256,
+    /// The number of transactions in the last L2 block
+    pub(crate) txs_len: usize,
+}