It can be useful to always return the fallback key when attempting to
claim keys. This adds an unstable endpoint for `/keys/claim` which
always returns fallback keys in addition to one-time-keys.
The fallback key(s) are not marked as "used" unless there are no
corresponding OTKs.
This is currently defined in MSC3983 (although likely to be split out
to a separate MSC). The endpoint shape may change or be requested
differently (i.e. a keyword parameter on the current endpoint), but the
core logic should be reasonable.
Add logic to ClientRestResource to decide whether to mount servlets
or not based on whether the current process is a worker.
This is clearer to see what a worker runs than the completely separate /
copy & pasted list of servlets being mounted for workers.
* Validate device_keys for C-S /keys/query requests
Closes#10354
A small, not particularly critical fix. I'm interested in seeing if we
can find a more systematic approach though. #8445 is the place for any discussion.
