* 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
* Adding SetFileSearchableContent plugin API endpoint
* Fixing CI problems
* Fixing CI problems
* Fixing CI problems
* Fixing CI problems
* Fixing CI problems
* Exposing it to the public API
* Fix CI problems
* Adding SetSearchableContent to the pluginapi File struct
It was a good decision in hindsight to keep the public module as 0.x
because this would have been a breaking change again.
https://mattermost.atlassian.net/browse/MM-53032
```release-note
Changed the Go module path from github.com/mattermost/mattermost-server/server/v8 to github.com/mattermost/mattermost/server/v8.
For the public facing module, it's path is also changed from github.com/mattermost/mattermost-server/server/public to github.com/mattermost/mattermost/server/public
```
