* refactor: convert channel_moderation files to ts
- convert js files to ts
- update data types accordingly
- fix lint issues
Fixes: #21332
* fix: update argument type for visitChannel
- update type
- fix types issues
* refactor: change return type for getAdminAccount()
- change return type to getAdminAccount as UserProfile
* Add descriptions to test cases for getNeededAtMentionedUsernames
* MM-59854 Load users who are at-mentioned in message attachment fields
* MM-59854 Add server support for at-mentioning users in message attachment fields
* Migrate support/external_commands from JS to TS
* MM-59584 Ensure that at-mentions never show in other message attachment fields
* MM-59584 Add E2E tests for how we load users based on at mentions
* Use new E2E test helpers in other places
* Update snapshots
