[SECURITY] Test XSS in dismissed review

It's possible for reviews to not be assiocated with users, when they
were migrated from another forge instance. In the migration code,
there's no sanitization check for author names, so they could contain
HTML tags and thus needs to be properely escaped.

(cherry picked from commit ca798e4cc2)

tests/integration/fixtures/TestXSSReviewDismissed/comment.yml

@@ -0,0 +1,9 @@
+-
+  id: 1000
+  type: 32 # dismiss review
+  poster_id: 2
+  issue_id: 2 # in repo_id 1
+  content: "XSS time!"
+  review_id: 1000
+  created_unix: 1700000000
+  updated_unix: 1700000000

tests/integration/fixtures/TestXSSReviewDismissed/review.yml

@@ -0,0 +1,8 @@
+-
+  id: 1000
+  type: 1
+  issue_id: 2
+  original_author: "Otto <script class='evil'>alert('Oh no!')</script>"
+  content: "XSS time!"
+  updated_unix: 1700000000
+  created_unix: 1700000000

tests/integration/xss_test.go

@@ -13,6 +13,7 @@ import (
 	"testing"
 	"time"
 
+	issues_model "code.gitea.io/gitea/models/issues"
 	"code.gitea.io/gitea/models/unittest"
 	user_model "code.gitea.io/gitea/models/user"
 	"code.gitea.io/gitea/modules/git"
@@ -112,3 +113,17 @@ func TestXSSWikiLastCommitInfo(t *testing.T) {
 		})
 	})
 }
+
+func TestXSSReviewDismissed(t *testing.T) {
+	defer tests.AddFixtures("tests/integration/fixtures/TestXSSReviewDismissed/")()
+	defer tests.PrepareTestEnv(t)()
+
+	review := unittest.AssertExistsAndLoadBean(t, &issues_model.Review{ID: 1000})
+
+	req := NewRequest(t, http.MethodGet, fmt.Sprintf("/user2/repo1/pulls/%d", +review.IssueID))
+	resp := MakeRequest(t, req, http.StatusOK)
+	htmlDoc := NewHTMLParser(t, resp.Body)
+
+	htmlDoc.AssertElement(t, "script.evil", false)
+	assert.Contains(t, htmlDoc.Find("#issuecomment-1000 .dismissed-message").Text(), `dismissed Otto <script class='evil'>alert('Oh no!')</script>’s review`)
+}