Creates a new push-subscription-manager group and an associated
right, manage-all-push-subscriptions. The purpose of this is to
allow privileged accounts to purge expired subscriptions from the
database on behalf of other users. A user with this right will be
permitted to delete any subscription from the DB based on the token
alone. For all other users, deletion requests will be limited to
those associated with the requesting user's central ID.
This right will be granted to a bot account on Metawiki associated
with the Wikimedia push notifications service, and the push
notifications service account will make push subscription delete
requests to the API for subscriptions for which vendor APIs return bad
subscription responses.
Additionally, the providertoken parameter to ApiPushSubscriptionDelete
is updated to allow multiple providertoken values.
Bug: T259148
Change-Id: Ia6c17588ee94e6be74e5e3a75eb33e38f172fc93
