* POC for API handler opts modifier
* Made upload POSt api a file upload API
* Specified file upload local API
* Specified file upload local API
* Specified file upload API
* Simplified handler params
* Added basic security checks
* Fixed i18n
* used type for API handler options
* Removed limited reader from util deserializers (#26263)
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
```
