Improve status updates (#561)

- link to specific proc (only general build before)
- set status for all procs (before: only for the whole build on some SCMs)
- set status after restart
- set status to pending after waiting for approval
- make status of gitlab, gitea & github equal
- dedupe status update code
- dedupe `PostBuild` code

close #410, close #297, close #459, close #521

server/remote/coding/coding.go

@@ -243,7 +243,7 @@ func (c *Coding) Dir(ctx context.Context, u *model.User, r *model.Repo, b *model
 }
 
 // Status sends the commit status to the remote system.
-func (c *Coding) Status(ctx context.Context, u *model.User, r *model.Repo, b *model.Build, link string, proc *model.Proc) error {
+func (c *Coding) Status(ctx context.Context, u *model.User, r *model.Repo, b *model.Build, proc *model.Proc) error {
 	// EMPTY: not implemented in Coding OAuth API
 	return nil
 }