System level global webhook

[lunny]

I prefer to add system level global webhooks UI on admin panel. Administrators of gitea instance could add or remove system webhooks.

All system webhooks will not be displayed in repositories webhook settings ui but only displayed on admin panel. When an event is triggered, then all system webhooks, organization webhooks and repository webhooks will be requested.

A system webhook will help administrator to do statistics/backup/update depends systems and etc.

[Mikaela]

I think this is a duplicate of #4456

[0x5c]

@Mikaela
#4456 calls for user webhooks, that are essentially notifications.
This, however, calls for admin webhooks, which would run for all repositories on the instance.

[Mikaela]

Actually it says:

Feature Request: support for personal webhooks and site-wide webhooks
...
It is also useful to have site-wide webhooks that react on all repos for those who want to do some "logging to slack" kinda stuff.

and I think site-wide webhooks and system level global webhooks are the same thing, but I don't mind either way and probably won't comment here further.