perf(katana-rpc): spawn blocking tasks (#1456)

Resolves #1448

Creates new crate under `katana`, `katana-tasks`, for managing spawning blocking tasks. RPC calls that mostly perform blocking tasks are now sent to their designated threadpools and won't block the async threads.

- `TokioTaskSpawner`: mainly for spawning blocking IO-bound tasks (ie reading from storage)
- `BlockingThreadPool`: mainly for spawning expensive CPU-bound tasks

Depends on #1455 because now the RPC requests (that used to block the thread before) have to wait for the blocking tasks to finish and thus may be idling for more than 2 seconds which will result in a connection timeout.

Doing `sozo migrate` on 2s timeout will failed when calling `/esimateFee` for estimating the World contract declare tx with error `connection closed before message completed`.

Raw error message from `sozo` against the new changes:
```console
Caused by:
    Failed to deploy world: Failed to migrate world: Migrator(Provider(Other(TransportError(Reqwest(reqwest::Error { kind: Request, url: Url { scheme: "http", cannot_be_a_base: false, username: "", password: None, host: Some(Domain("localhost")), port: Some(5050), path: "/", query: None, fragment: None }, source: hyper::Error(IncompleteMessage) })))))
```

crates/katana/core/src/sequencer.rs

@@ -267,8 +267,9 @@ impl KatanaSequencer {
         self.backend.chain_id
     }
 
-    pub fn block_number(&self) -> BlockNumber {
-        BlockNumberProvider::latest_number(&self.backend.blockchain.provider()).unwrap()
+    pub fn block_number(&self) -> SequencerResult<BlockNumber> {
+        let num = BlockNumberProvider::latest_number(&self.backend.blockchain.provider())?;
+        Ok(num)
     }
 
     pub fn block_tx_count(&self, block_id: BlockIdOrTag) -> SequencerResult<Option<u64>> {
@@ -300,7 +301,7 @@ impl KatanaSequencer {
         Ok(count)
     }
 
-    pub async fn nonce_at(
+    pub fn nonce_at(
         &self,
         block_id: BlockIdOrTag,
         contract_address: ContractAddress,
@@ -352,7 +353,7 @@ impl KatanaSequencer {
         Ok(tx)
     }
 
-    pub async fn events(
+    pub fn events(
         &self,
         from_block: BlockIdOrTag,
         to_block: BlockIdOrTag,

crates/katana/rpc/Cargo.toml

@@ -12,6 +12,7 @@ katana-primitives = { path = "../primitives" }
 katana-provider = { path = "../storage/provider" }
 katana-rpc-types = { path = "rpc-types" }
 katana-rpc-types-builder = { path = "rpc-types-builder" }
+katana-tasks = { path = "../tasks" }
 
 anyhow.workspace = true
 cairo-lang-starknet = "2.3.1"