Add can_share to capabilities report

[phil-davis]

It would be useful for clients to be able to find out if their current user has the ability to share. At the moment the client can examine lots of system-wide capabilities (e.g. if sharing is off, then certainly the current user cannot share anything!) But the user could be, for example, in a group that is excluded from sharing. In that case the other capabilities will all look like sharing is possible, the client will present the end-user with some UI for sharing, then when the user tries to share something it will fail.

In the future there might be other combinations of settings that determine if a user "can share". Having a common capability where this "generic/logical" ability is reported seems useful.

1. Add a capability can_share
2. can_share is true if the current user is able to share "stuff". If other system-wide settings restrict what "stuff" can be shared in what ways to some subset of things (e.g. public link sharing is disabled...) then can_share is still true.
3. can_share is false if sharing is completely disabled on the system.
4. can_share is false if sharing is completely disabled for the user.

[phil-davis]

Derived from discussions in issue #31576 and PR #31580

Proposed PR for can_share capability: #31816

[ownclouders]

GitMate.io thinks the contributor most likely able to help you is @PVince81.

Possibly related issues are #27622 (Add capability indicating support of multiple link shares), #31816 (Can share capability), #31580 (Add exclude_groups_from_sharing to capabilities), #25373 (Add search support on the REPORT method), and #12289 (Add OCS capability to advertise server to server sharing support).

[phil-davis]

Backport stable10 #31824 is waiting until after 10.0.9 is out.

[phil-davis]

This is done - the backport will get merged in due course.