Replace deprecated methods assertText, assertNoText, assertRaw, assertNoRaw and assertTitle in tests

I replaced uses of assertText() with assertSession()->pageTextContains(); assertNoText() with assertSession()->pageTextNotContains(); assertRaw() with assertSession()->responseContains(); assertNoRaw() with assertSession()->responseNotContains(); and assertTitle() with assertSession()->titleEquals(). Then committed the changes and opened an MR. Please kindly review.

Thank you kindly for your review @beatrizrodrigues and @AdamPS. Here are some comments about @AdamPS notes on the MR.

1. I removed the Html::escape() in SimplenewsPersonalizationFormsTest.php because, unlike the deprecated assertText(), in pageTextContains() the passed text should be HTML decoded, exactly as a human sees it in the browser. So the Html::escape was being used to sanitize/encode the randomString generated (like converting ‘<’ to ‘<’) and then asserting if it was in the page, since assertText() filters the page Html. With pageTextContains() that was not needed anymore.

To try and make it more clear, I attached a .txt with the output of the test with assertText() if I remove the Html::escape. The randomString generated was ”z_{\^A7V7x>&=2))A0]” and the output the assertText() looked for was the encoded version of it, “z_{\^A7V7x>&=2))A0]”. With pageTextContains() we assert using the decoded Html directly, so no need to use Html::escape anymore. If it doesn’t make sense and you think I need to change something, feel free to correct me.

2. I was not able to remove the t() from some of the assertRaw() methods initially because, like in SimplenewsPersonalizationFormsTest.php, the page is returning “The email address <em class="placeholder">s88x@example.com</em> belongs to a blocked user.".

Without the t() the tests fail with the following error: The string "The email address nctb@example.com belongs to a blocked user." was not found anywhere in the HTML response of the current page.
Also this happens with some others assertRaw() that were in use. In SimplenewsSubscribeTest.php I get "Are you sure you want to confirm your subscription for <em class="placeholder">n*****@e*****.com</em>?" from the page.

I researched about it and found that the placeholder tag used in some files of the codebase is the % one, like on line 199 of SubscriptionsBlockForm.php:
$message = $this->t('The email address %mail belongs to a blocked user.', ['%mail' => $mail]);
so the replacement value is wrapped in <em> tags on the page. I guess the t() function was keeping the tag from being sanitized. I think we could add the tags to the test assertion like in the commit I just made, which removed all t() calls in the methods I replaced, or change the placeholder tag (to @) in the code itself.

3. Thanks for the tip about string interpolation, I tried to use it in some places where I saw it fit better, if you think there are any others I can change them too.

I think I addressed all the comments, if I missed any or if something is wrong I will gladly try to fix it again.