Disallow untyped defs in synapse._scripts (#12422)

Of note: 

* No untyped defs in `register_new_matrix_user`

This one might be contraversial. `request_registration` has three
dependency-injection arguments used for testing. I'm removing the
injection of the `requests` module and using `unitest.mock.patch` in the
test cases instead.

Doing `reveal_type(requests)` and `reveal_type(requests.get)` before the
change:

```
synapse/_scripts/register_new_matrix_user.py:45: note: Revealed type is "Any"
synapse/_scripts/register_new_matrix_user.py:46: note: Revealed type is "Any"
```

And after:

```
synapse/_scripts/register_new_matrix_user.py:44: note: Revealed type is "types.ModuleType"
synapse/_scripts/register_new_matrix_user.py:45: note: Revealed type is "def (url: Union[builtins.str, builtins.bytes], params: Union[Union[_typeshed.SupportsItems[Union[builtins.str, builtins.bytes, builtins.int, builtins.float], Union[builtins.str, builtins.bytes, builtins.int, builtins.float, typing.Iterable[Union[builtins.str, builtins.bytes, builtins.int, builtins.float]], None]], Tuple[Union[builtins.str, builtins.bytes, builtins.int, builtins.float], Union[builtins.str, builtins.bytes, builtins.int, builtins.float, typing.Iterable[Union[builtins.str, builtins.bytes, builtins.int, builtins.float]], None]], typing.Iterable[Tuple[Union[builtins.str, builtins.bytes, builtins.int, builtins.float], Union[builtins.str, builtins.bytes, builtins.int, builtins.float, typing.Iterable[Union[builtins.str, builtins.bytes, builtins.int, builtins.float]], None]]], builtins.str, builtins.bytes], None] =, data: Union[Any, None] =, headers: Union[Any, None] =, cookies: Union[Any, None] =, files: Union[Any, None] =, auth: Union[Any, None] =, timeout: Union[Any, None] =, allow_redirects: builtins.bool =, proxies: Union[Any, None] =, hooks: Union[Any, None] =, stream: Union[Any, None] =, verify: Union[Any, None] =, cert: Union[Any, None] =, json: Union[Any, None] =) -> requests.models.Response"
```

* Drive-by comment in `synapse.storage.types`

* No untyped defs in `synapse_port_db`

This was by far the most painful. I'm happy to break this up into
smaller pieces for review if it's not managable as-is.

1 files changed, 10 insertions, 10 deletions

diff --git a/synapse/_scripts/update_synapse_database.py b/synapse/_scripts/update_synapse_database.py

index 736f58836d..c443522c05 100755
--- a/synapse/_scripts/update_synapse_database.py
+++ b/synapse/_scripts/update_synapse_database.py
@@ -38,25 +38,25 @@ logger = logging.getLogger("update_database")
 class MockHomeserver(HomeServer):
     DATASTORE_CLASS = DataStore  # type: ignore [assignment]
 
-    def __init__(self, config, **kwargs):
+    def __init__(self, config: HomeServerConfig):
         super(MockHomeserver, self).__init__(
-            config.server.server_name, reactor=reactor, config=config, **kwargs
-        )
-
-        self.version_string = "Synapse/" + get_distribution_version_string(
-            "matrix-synapse"
+            hostname=config.server.server_name,
+            config=config,
+            reactor=reactor,
+            version_string="Synapse/"
+            + get_distribution_version_string("matrix-synapse"),
         )
 
 
-def run_background_updates(hs):
+def run_background_updates(hs: HomeServer) -> None:
     store = hs.get_datastores().main
 
-    async def run_background_updates():
+    async def run_background_updates() -> None:
         await store.db_pool.updates.run_background_updates(sleep=False)
         # Stop the reactor to exit the script once every background update is run.
         reactor.stop()
 
-    def run():
+    def run() -> None:
         # Apply all background updates on the database.
         defer.ensureDeferred(
             run_as_background_process("background_updates", run_background_updates)
@@ -67,7 +67,7 @@ def run_background_updates(hs):
     reactor.run()
 
 
-def main():
+def main() -> None:
     parser = argparse.ArgumentParser(
         description=(
             "Updates a synapse database to the latest schema and optionally runs background updates"