* Adds type hints to the groups servlet and stringutils code.
* Assert the maximum length of some input values for spec compliance.

* Handle the case of lxml not finding a document tree.
* Parse the document encoding from the XML tag.

New API /_synapse/admin/rooms/{roomId}/context/{eventId}

Signed-off-by: Joseph Arnault <computerdude90042@outlook.com>

Signed-off-by: Dan Callahan <danc@element.io>

Co-authored-by: compu42 <56663749+compu42@users.noreply.github.com>

Fixes some exceptions if the room state isn't quite as expected.
If the expected state events aren't found, try to find them in the
historical room state. If they still aren't found, fallback to a reasonable,
although ugly, value.

This fixes the Jinja2 templates for the mapping provider.

* Adds proper dependencies.
* Minor fixes in database layer.

* fix validation and don't use built-in validation UI

Co-authored-by: Bruno Windels <brunow@element.io>

config: Add detail to auto_join_rooms comment

Signed-off-by: Gary Dykstra <gary@dykstranet.com>

Also add a few more IP ranges to the default blacklist.

This could arguably replace the existing admin API for `/members`, however that is out of scope of this change.

This sort of endpoint is ideal for moderation use cases as well as other applications, such as needing to retrieve various bits of information about a room to perform a task (like syncing power levels between two places). This endpoint exposes nothing more than an admin would be able to access with a `select *` query on their database.

fixes #9171

* Fixes a case where no summary text was returned.
* The use of messages_from_person vs. messages_from_person_and_others
  was tweaked to depend on whether there was 1 sender or multiple senders,
  not based on if there was 1 room or multiple rooms.