Fix XSS vulnerabilities (#29336)

- The Wiki page did not sanitize author name
- the reviewer name on a "dismiss review" comment is also affected
- the migration page has some spots

---------

Signed-off-by: jolheiser <john.olheiser@gmail.com>
Co-authored-by: Gusted <postmaster@gusted.xyz>
Co-authored-by: jolheiser <john.olheiser@gmail.com>

templates/repo/issue/view_content/comments.tmpl

@@ -615,7 +615,7 @@
 						{{else}}
 							{{$reviewerName = .Review.OriginalAuthor}}
 						{{end}}
-						{{ctx.Locale.Tr "repo.issues.review.dismissed" $reviewerName $createdStr | Safe}}
+						<span class="dismissed-message">{{ctx.Locale.Tr "repo.issues.review.dismissed" ($reviewerName | Escape) $createdStr | Safe}}</span>
 					</span>
 				</div>
 				{{if .Content}}