Add metrics for mobile versions snapshots (#28191)

* Add metrics for mobile versions snapshots

* Add notifications disabled and fix lint

* Address feedback

* Verify all references to JobTypeActiveUsers

* Fix typos

* Improve platform values

* Add test and MySQL support

server/channels/store/store.go

@@ -503,6 +503,7 @@ type SessionStore interface {
 	Save(c request.CTX, session *model.Session) (*model.Session, error)
 	GetSessions(c request.CTX, userID string) ([]*model.Session, error)
 	GetLRUSessions(c request.CTX, userID string, limit uint64, offset uint64) ([]*model.Session, error)
+	GetMobileSessionMetadata() ([]*model.MobileSessionMetadata, error)
 	GetSessionsWithActiveDeviceIds(userID string) ([]*model.Session, error)
 	GetSessionsExpired(thresholdMillis int64, mobileOnly bool, unnotifiedOnly bool) ([]*model.Session, error)
 	UpdateExpiredNotify(sessionid string, notified bool) error