Fix Potential XSS in HTML Markup

Problem/Motivation

In _acquia_optimize_footer method: https://git.drupalcode.org/project/acquia_optimize/-/blob/1.x/acquia_opt...
There's a scope of potential XSS which we can avoid.

Steps to reproduce

Proposed resolution

Convert string to Render array

Something like this:

/ Replace HTML string construction with render array
$footer = [
  '#type' => 'container',
  '#attributes' => ['class' => ['optimize-footer']],
  'info' => [
    '#type' => 'html_tag',
    '#tag' => 'p',
    '#attributes' => ['class' => ['scan-info']],
    '#markup' => t('Results are not synchronized to your Acquia Optimize account. To learn more visit'),
  ],
  'link' => [
    '#type' => 'link',
    '#title' => t('Acquia Docs.'),
    '#url' => Url::fromUri('https://docs.acquia.com/acquia-optimize/how-do-scan/quick-scan#section-faq'),
    '#attributes' => ['target' => '_blank'],
  ],
  'account_button' => [
    '#type' => 'link',
    '#title' => t('Go to your Optimize account'),
    '#url' => Url::fromUri('https://new.monsido.com'),
    '#attributes' => [
      'target' => '_blank',
      'class' => ['optimize-account-button'],
    ],
  ],
];

// Use the render array instead of the HTML string
$form['footer'] = $footer;