MM-56083 Add PatchMultipleMembersNotifyProps plugin API (#25690)

* Add ChannelStore.UpdateMultipleMembersNotifyProps

* Make UpdateMultipleMembersNotifyProps return updated values from the DB

* Add UpdateChannelMembersNotifications plugin API

* Extract i18n

* Fix style

* Make layers

* Change to PatchMultipleMembersNotifyProps

* Add limit to PatchChannelMembersNotifyProps

* Add additional unit tests

* Address feedback

* Lowercase decodeJSON

* Have PatchMultipleMembersNotifyProps update LastUpdateAt

* Fix tests that relied on unreliable return order

* Fix i18n

server/channels/store/store.go

@@ -225,6 +225,7 @@ type ChannelStore interface {
 	// UpdateMemberNotifyProps patches the notifyProps field with the given props map.
 	// It replaces existing fields and creates new ones which don't exist.
 	UpdateMemberNotifyProps(channelID, userID string, props map[string]string) (*model.ChannelMember, error)
+	PatchMultipleMembersNotifyProps(members []*model.ChannelMemberIdentifier, notifyProps map[string]string) ([]*model.ChannelMember, error)
 	GetMembers(channelID string, offset, limit int) (model.ChannelMembers, error)
 	GetMember(ctx context.Context, channelID string, userID string) (*model.ChannelMember, error)
 	GetMemberLastViewedAt(ctx context.Context, channelID string, userID string) (int64, error)