Changes:
* Adds API reference docs for the delete snapshot repo API.
* Corrects an error in the delete snapshot repo API spec. Comma-separated
repository names are not supported.
* Relocates the existing delete snapshot repo API example docs.
* Allow Deleting Multiple Snapshots at Once (#55474)
Adds deleting multiple snapshots in one go without significantly changing the mechanics of snapshot deletes otherwise.
This change does not yet allow mixing snapshot delete and abort. Abort is still only allowed for a single snapshot delete by exact name.