Refactor RPC subscriptions account handling (#9888)

* Switch subscriptions to use commitment instead of confirmations

* Add bank method to return account and last-modified slot

* Add last_modified_slot to subscription data and use to filter account subscriptions

* Update tests to non-zero last_notified_slot

* Add accounts subscriptions to test; fails at higher tx load

* Pass BankForks to RpcSubscriptions

* Use BankForks on add_account_subscription to properly initialize last_notified_slot

* Bundle subscriptions

* Check for non-equality

* Use commitment to initialize last_notified_slot; revert context.slot chage

core/src/commitment.rs

@@ -162,6 +162,24 @@ impl BlockCommitmentCache {
         }
     }
 
+    #[cfg(test)]
+    pub fn new_for_tests_with_blockstore_bank(
+        blockstore: Arc<Blockstore>,
+        bank: Arc<Bank>,
+        root: Slot,
+    ) -> Self {
+        let mut block_commitment: HashMap<Slot, BlockCommitment> = HashMap::new();
+        block_commitment.insert(0, BlockCommitment::default());
+        Self {
+            block_commitment,
+            blockstore,
+            total_stake: 42,
+            largest_confirmed_root: root,
+            bank,
+            root,
+        }
+    }
+
     #[cfg(test)]
     pub(crate) fn set_get_largest_confirmed_root(&mut self, root: Slot) {
         self.largest_confirmed_root = root;