Convert assertions involving use of xpath on links to WebAssert

I read all the conversions and they all look sensible. Two changes look to be out of scope, and a few comments about how I wish we could do things another way but probably out of scope to add functionality to WebAssert here? Will wait for your response but I think this is close to RTBC.

I've re-checked all the changes in this patch and they all look OK to me.

Committed/pushed to 9.3.x.

We should backport to 9.2.x to keep the tests in sync for other patches, but this doesn't cherry-pick cleanly so tagging for a re-roll.

Let's see if I can reroll this for 9.2.x

Looks like a random fail #3210432: [random test failure] LayoutBuilderQuickEditTest::testQuickEditIgnoresDuplicateFields(), let's give TestBot another go.

Compared the patches with diff -u <(curl https://git.drupalcode.org/project/drupal/-/merge_requests/838.diff) <(curl https://git.drupalcode.org/project/drupal/-/merge_requests/1024.diff) and the one difference is the change to file_url_transform_relative() which is correct, so this looks OK to me. Also looks like a random fail last time, so this is RTBC.

Needs another re-roll.

Rebased against 9.2.x, one merge conflict that was trivial to solve:

--- a/core/modules/views_ui/tests/src/Functional/DisplayAttachmentTest.php
+++ b/core/modules/views_ui/tests/src/Functional/DisplayAttachmentTest.php
@@@ -45,9 -45,8 +45,8 @@@ class DisplayAttachmentTest extends UIT
      $this->submitForm(['displays[page_1]' => 1], 'Apply');
      // Options summary should be escaped.
      $this->assertSession()->assertEscaped('<em>Page</em>');
 -    $this->assertNoRaw('<em>Page</em>');
 +    $this->assertSession()->responseNotContains('<em>Page</em>');
-     $result = $this->xpath('//a[@id = :id]', [':id' => 'views-attachment-1-displays']);
-     $this->assertEquals(t('Page'), $result[0]->getAttribute('title'));
+     $this->assertSession()->elementAttributeContains('xpath', '//a[@id = "views-attachment-1-displays"]', 'title', 'Page');
      $this->submitForm([], 'Save');
  
      $view = Views::getView('test_attachment_ui');

Committed c3a97f5 and pushed to 9.2.x. Thanks!