Issue writers perms can modify issues (#10623)

Signed-off-by: jolheiser <john.olheiser@gmail.com>

routers/repo/pull.go

@@ -622,6 +622,8 @@ func ViewPullFiles(ctx *context.Context) {
 		return
 	}
 	getBranchData(ctx, issue)
+	ctx.Data["IsIssuePoster"] = ctx.IsSigned && issue.IsPoster(ctx.User.ID)
+	ctx.Data["IsIssueWriter"] = ctx.Repo.CanWriteIssuesOrPulls(issue.IsPull)
 	ctx.HTML(200, tplPullFiles)
 }