* Remove the need to call `/initialSync` in `getMessagesByUserIn`.
At the moment we call `/initialSync` to give a `from` token to `/messages`.
In this PR we instead do not provide a `from` token when calling `/messages`,
which has recently been permitted in the spec
Technically this is still unstable in the spec
https://spec.matrix.org/unstable/client-server-api/#get_matrixclientv3roomsroomidmessageshttps://github.com/matrix-org/matrix-spec/pull/1002
Synapse has supported this for over 2 years and Element web depends on it for threads.
https://github.com/matrix-org/matrix-js-sdk/pull/2065
Given that redactions are super heavy in Mjolnir already and have been reported
as barely functional on matrix.org I believe we should also adopt this approach as
if for some reason the spec did change before the next release (1.3) (extremely unlikely) we can revert this commit.
This is so that the context of failing callbacks are not lost.
We also await during pagination and not after so that if a call to the callback fails, we will not call it again.
Related to https://github.com/matrix-org/mjolnir/pull/132.
The old code would call `/sync` with this filter. If a token was
provided in the response of `/sync` for earlier messages, it would
then use this same filter to call `/rooms/messages`. However, this
filter does not do anything on that endpoint when we know the id of
the sender, as it requires a RoomEventFilter and there is no warning
or error from synapse about the structure of the filter being wrong.
This was not noticed until after the related PR because `/sync` with
the filter would usually be able to provide a user's
entire history in one room. This is because in most cases a user is banned/redacted
shortly after joining a room.
In the case that `/rooms/messages` was called for more events, the method would
always paginate the timeline up until the limit or the end of the room
history, which is only the expected behavior when matching the sender
with a "glob".
