[ENH] implement append, commit and flush for spann segment and index (#…

…3084)

## Description of changes

*Summarize the changes made by this PR.*
 - New functionality
	 - Implement append, commit and flush for spann segment and index. Current implementation does split and/or reassign. They will be followed up in the next PR.

## Test plan
*How are these changes tested?*
- [x] Tests pass locally with `pytest` for python, `yarn test` for js, `cargo test` for rust

## Documentation Changes
None

rust/blockstore/src/types/writer.rs

@@ -80,6 +80,23 @@ impl BlockfileWriter {
         }
     }
 
+    pub async fn get_owned<
+        K: Key + Into<KeyWrapper> + ArrowWriteableKey,
+        V: Value + Writeable + ArrowWriteableValue,
+    >(
+        &self,
+        prefix: &str,
+        key: K,
+    ) -> Result<Option<V::PreparedValue>, Box<dyn ChromaError>> {
+        match self {
+            BlockfileWriter::MemoryBlockfileWriter(_) => todo!(),
+            BlockfileWriter::ArrowUnorderedBlockfileWriter(writer) => {
+                writer.get_owned::<K, V>(prefix, key).await
+            }
+            BlockfileWriter::ArrowOrderedBlockfileWriter(_) => todo!(),
+        }
+    }
+
     pub fn id(&self) -> uuid::Uuid {
         match self {
             BlockfileWriter::MemoryBlockfileWriter(writer) => writer.id(),