REST API PUT methods do not use Etag or other edit conflict avoidance

[dpk]

Is your feature request related to a problem? Please describe

In the REST API many settings on endpoints etc. can only be edited by replacing the entire JSON settings for that thing with a PUT request. There is no way to ensure one small edit does not clobber an edit made by another client simultaneously.

Describe the solution you'd like

Either GET requests for REST resources which are updated by PUT should include an Etag or some other version hash which a subsequent PUT request can include (If-Match header), and the PUT request should be rejected if that no longer corresponds to the latest version when saved

Describe alternatives you've considered

HTTP PATCH would be another option provided you could ensure that the end result after applying the patch still makes sense

Additional context

No response