Add a cache around server ACL checking (#16360)

* Pre-compiles the server ACLs onto an object per room and
  invalidates them when new events come in.
* Converts the server ACL checking into Rust.

stubs/synapse/synapse_rust/acl.pyi

@@ -0,0 +1,21 @@
+# Copyright 2023 The Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from typing import List
+
+class ServerAclEvaluator:
+    def __init__(
+        self, allow_ip_literals: bool, allow: List[str], deny: List[str]
+    ) -> None: ...
+    def server_matches_acl_event(self, server_name: str) -> bool: ...