expose hashbrown::HashMap in primitives

[andy-thomason]

Issue: #344

EVM::transact returns ResultAndState which contains type State = HashMap<B160, Account>;

State is internal to revm and requires hashbrown to form the type in user-called code.

Likewise, Account contains:

    pub storage: HashMap<U256, StorageSlot>,

By exposing HashMap in primitives it provides user the ability to use this type independently and insulates them from changes to the type.