this makes it a bit clearer what's going on.

Fixes https://github.com/matrix-org/synapse/issues/8185

... to `_get_e2e_device_keys_and_signatures_txn`, to better reflect what it
does.

This is so that we can use it for the backfill events stream.

This is due to compatibility issues with old Python versions.

* Move `get_devices_with_keys_by_user` to `EndToEndKeyWorkerStore`

this seems a better fit for it.

This commit simply moves the existing code: no other changes at all.

* Rename `get_devices_with_keys_by_user`

to better reflect what it does.

* get_device_stream_token abstract method

To avoid referencing fields which are declared in the derived classes, make
`get_device_stream_token` abstract, and define that in the classes which define
`_device_list_id_gen`.

... and to show that it does something slightly different to
`_get_e2e_device_keys_txn`.

`include_all_devices` and `include_deleted_devices` were never used (and
`include_deleted_devices` was broken, since that would cause `None`s in the
result which were not handled in the loop below.

Add some typing too.

This fixes a bug where having multiple callers waiting on the same
stream and position will cause it to try and compare two deferreds,
which fails (due to the sorted list having an entry of `Tuple[int,
Deferred]`).

There's not much point in returning all the others, and some people have a
silly number of devices.

This is split out from https://github.com/matrix-org/synapse/pull/7438, which had gotten rather large.

`LoginRestServlet` has a couple helper methods, `login_submission_legacy_convert` and `login_id_thirdparty_from_phone`. They're primarily used for converting legacy user login submissions to "identifier" dicts ([see spec](https://matrix.org/docs/spec/client_server/r0.6.1#post-matrix-client-r0-login)). Identifying information such as usernames or 3PID information used to be top-level in the login body. They're now supposed to be put inside an [identifier](https://matrix.org/docs/spec/client_server/r0.6.1#identifier-types) parameter instead.

#7438's purpose is to allow using the new identifier parameter during User-Interactive Authentication, which is currently handled in AuthHandler. That's why I've moved these helper methods there. I also moved the refactoring of these method from #7438 as they're relevant.

This was forgotten in #8164.

This ensures systemctl start matrix-synapse returns only after synapse
is actually started, which is very useful for automated deployments.

Fixes #5761

Signed-off-by: Dexter Chua <dec41@srcf.net>

#8174 removed the `is_guest` parameter from `get_room_data`, at the same time that #8157 was merged using it, colliding together to break unit tests on develop.

This PR removes the `is_guest` parameter from the call in the broken test.

Uses the same changelog as #8174.