Combine and limit delete-notification pushes

[nickvergessen]

Currently all mobile clients always receive all delete-pushes. iOS ignores silent background notifications if there are too many, so we plan to limit and combine them:

• [ ] Only send talk to talk apps and all others to the files app
• [ ] Combine the multiple deletes into 1 push, so instead of:

			[
				'nid' => 13,
				'delete' => true,
			]

			[
				'nid' => 42,
				'delete' => true,
			]

			[
				'nid' => 23,
				'delete' => true,
			]

the Talk iOS app receives:

			[
				'nids' => [13, 42, 23],
				'delete-multiple' => true,
			]

[blizzz]

moving to 25

[SystemKeeper]

Fixed by https://github.com/nextcloud/notifications/pull/1429 and included in 26.0.0 ?