Cache PullRequest Divergence (#10914)

* Cache PullRequest Divergence

* only re-calc divergence if AddTestPullRequestTask() is exec

* migrate already open pulls

* finalize

* take care of closed&not-merged+deleted-branch pull requests

* fix nil pointer exeption

Signed-off-by: 6543 <6543@obermui.de>

* try this

* no error its a warn

* init gitea-repositories-meta

* dont use gitDivergence type

* CI.restart()

* CI.restart()

* CI.restart()

* CI.restart()

* check IsUserAllowedToUpdate independend from CommitsBehind

templates/repo/issue/view_content/pull.tmpl

@@ -305,7 +305,7 @@
 						</div>
 					{{end}}
 				{{end}}
-				{{if and .Divergence (gt .Divergence.Behind 0)}}
+				{{if gt .Issue.PullRequest.CommitsBehind 0}}
 				<div class="ui very compact branch-update grid">
 						<div class="row">
 						<div class="item text gray eleven wide left floated column">