Detect and show force pushes in PR

[jolheiser]

Similar to GH, a pull request should show when its branch has been force-pushed to.
This is handy/relevant information to know, and might even help determine otherwise confusing behavior.

[bagasme]

@jolheiser What about the implementation?

[zeripath]

We need another comment type.

The detection code would go in to:

gitea/services/pull/pull.go

Line 217 in 4acca9d

func PushToBaseRepo(pr *models.PullRequest) (err error) {

Or could go in to the pre-receive hook... (Actually instead we should probably prevent direct update of refs/pull paths in pre-receive...)

[tgotwig]

Would be a really awesome feature! I miss it a lot 😬

[6543]

did #11167 fix this issue?

[lafriks]

Should be fixed by #11167, please reopen if it's not