Show edit title button on commits tab of PR, too (#25791)

All 3 tabs of the PR (Conversation, Commits and Files changed) should
show the edit title button.

Before this commit the edit button was not shown on commits tab

Screenshots:
After: 

![image](https://github.com/go-gitea/gitea/assets/1135157/d04c700c-dffc-4bcd-8108-cb64838af0c6)

Before:

![image](https://github.com/go-gitea/gitea/assets/1135157/b6795ad3-c994-461c-98aa-a7331c3e3877)

Just for reference the edit button in files changed tab:

![image](https://github.com/go-gitea/gitea/assets/1135157/5750640d-489f-4a71-8144-543ef42afb42)

Co-authored-by: Giteabot <teabot@gitea.io>

routers/web/repo/pull.go

@@ -723,6 +723,9 @@ func ViewPullCommits(ctx *context.Context) {
 	ctx.Data["Commits"] = commits
 	ctx.Data["CommitCount"] = len(commits)
 
+	ctx.Data["HasIssuesOrPullsWritePermission"] = ctx.Repo.CanWriteIssuesOrPulls(issue.IsPull)
+	ctx.Data["IsIssuePoster"] = ctx.IsSigned && issue.IsPoster(ctx.Doer.ID)
+
 	getBranchData(ctx, issue)
 	ctx.HTML(http.StatusOK, tplPullCommits)
 }