* Add some type hints to datastore
* newsfile
* change `Collection` to `List`
* refactor return type of `select_users_txn`
* correct type hint in `stream.py`
* Remove `Optional` in `select_users_txn`
* remove not needed return type in `__init__`
* Revert change in `get_stream_id_for_event_txn`
* Remove import from `Literal`
Part of #9744
Removes all redundant `# -*- coding: utf-8 -*-` lines from files, as python 3 automatically reads source code as utf-8 now.
`Signed-off-by: Jonathan de Jong <jonathan@automatia.nl>`
