Fix cannot reopen after pushing commits to a closed PR (#23189)

[sillyguodong]

Backport: #23189
Close: #22784

1. On GH, we can reopen a PR which was closed before after pushing commits. After reopening PR, we can see the commits that were pushed after closing PR in the time line. So the case of
   issue is a bug which needs to be fixed.

2. After closing a PR and pushing commits, headBranchSha is not equal to sha(which is the last commit ID string of reference). If the judgement exists, the button of reopen will not display. So, skip the judgement if the status of PR is closed.

3. Even if PR is already close, we should still insert comment record into DB when we push commits.
   So we should still call function CreatePushPullComment().

gitea/services/pull/pull.go

Lines 260 to 282 in 067b0c2

	prs, err := issues_model.GetUnmergedPullRequestsByHeadInfo(repoID, branch)
	if err != nil {
	log.Error("Find pull requests [head_repo_id: %d, head_branch: %s]: %v", repoID, branch, err)
	return
	}
	for _, pr := range prs {
	log.Trace("Updating PR[%d]: composing new test task", pr.ID)
	if pr.Flow == issues_model.PullRequestFlowGithub {
	if err := PushToBaseRepo(ctx, pr); err != nil {
	log.Error("PushToBaseRepo: %v", err)
	continue
	}
	} else {
	continue
	}
	AddToTaskQueue(pr)
	comment, err := CreatePushPullComment(ctx, doer, pr, oldCommitID, newCommitID)
	if err == nil && comment != nil {
	notification.NotifyPullRequestPushCommits(ctx, doer, pr, comment)
	}
	}

So, I add a switch(includeClosed) to the
GetUnmergedPullRequestsByHeadInfo func to control whether the status of PR must be open. In this case, by setting includeClosed to true, we can query the closed PR.

4. In the loop of comments, I use thelatestCloseCommentID variable to record the last occurrence of the close comment.
   In the go template, if the status of PR is closed, the comments whose type is CommentTypePullRequestPush(29) after latestCloseCommentID won't be rendered.

e.g.
1). The initial status of the PR is opened.

2). Then I click the button of Close. PR is closed now.

3). I try to push a commit to this PR, even though its current status is closed.

But in comments list, this commit do not display.This is as expected ：）

4). Click the Reopen button, the commit which is pushed after closing PR display now.

[jolheiser]

🎺 🤖