Convert filter_element_info() to Element classes

Rerolled for now without the hook_element_info() removal in light of #2326409: Annotate render element plugins

1. +++ b/core/modules/filter/src/Element/ProcessedText.php
   @@ -0,0 +1,154 @@
   +   * Note: Because filters can inject JavaScript or execute PHP code, security is
   +   * vital here. When a user supplies a text format, you should validate it using
   ...
   +   *     array (default) to skip no filter types. All of the format's filters will
   +   *     be applied, except for filters of the types that are marked to be skipped.
   ...
   +    // Give filters the chance to escape HTML-like data such as code or formulas.
   
   +++ b/core/modules/filter/src/Element/TextFormat.php
   @@ -0,0 +1,232 @@
   +   *   using the text format ID specified in #format or the user's default format
   ...
   +   *     available for this element. If omitted, all text formats that the current
   ...
   +    // If #allowed_formats is set, the list of formats must not be modified in any
   ...
   +    // 1. The 'always_show_fallback_choice' filter setting has not been activated.
   ...
   +    // or if the stored format does not exist. The 'administer filters' permission
   

   More then 80 chars.

2. +++ b/core/modules/filter/src/Element/ProcessedText.php
   @@ -0,0 +1,154 @@
   +      $format_id = filter_fallback_format();
   

   We can use \Drupal::config('filter.settings')->get('fallback_format'); here.

3. +++ b/core/modules/filter/src/Element/ProcessedText.php
   @@ -0,0 +1,154 @@
   +      \Drupal::logger('filter')->alert('Missing text format: %format.', array('%format' => $format_id));
   
   +++ b/core/modules/filter/src/Element/TextFormat.php
   @@ -0,0 +1,232 @@
   +    $user = \Drupal::currentUser();
   ...
   +    $element['value'] += \Drupal::service('element_info')->getInfo($element['#base_type']);
   ...
   +    if (!isset($element['#allowed_formats']) && !\Drupal::config('filter.settings')->get('always_show_fallback_choice')) {
   ...
   +    $user_is_admin = \Drupal::currentUser()->hasPermission('administer filters');
   

   We can inject these.

4. +++ b/core/modules/filter/src/Element/ProcessedText.php
   @@ -0,0 +1,154 @@
   +    /** @var \Drupal\filter\FilterBag $filters **/
   ...
   +    /** @var \Drupal\filter\Plugin\FilterInterface $filter **/
   

   I don't think we need this.

Thank you for the fixes.

Committed and pushed to 8.x. Thanks!