[MM-37984] Allow Desktop App to authenticate via external providers outside of the app on supported servers (#23795)

* WIP

* Add rate limiting for desktop token API

* Missing mocks

* Style fixes

* Update snapshots

* Maybe use an actual redirect link :P

* Refactoring for tests

* Add tests for server

* Fix lint issue

* Fix tests

* Fix lint

* Add front-end screen component

* Component logic

* Style changes

* Quick style fix

* Lint fixes

* Initial PR feedback

* Enable logging into the browser as well when completing the login process

* Refactor to push more logic to the other component

* Remove unnecessary helper code

* Fix i18n

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/public/model/user.go

@@ -62,6 +62,8 @@ const (
 	UserLocaleMaxLength   = 5
 	UserTimezoneMaxRunes  = 256
 	UserRolesMaxLength    = 256
+
+	DesktopTokenTTL = time.Minute * 3
 )
 
 //msgp:tuple User