Improve token validation

Problem/Motivation

The token modules includes token validation handling via token_element_validate(). The UX for entering tokens would be significantly improved if we warned users about invalid tokens.

Proposed resolution

Apply token_element_validate() to all text-based elements for all forms that support tokens,

Remaining tasks

• Add public \Drupal\webform\WebformTokenManager::elementValidate($form, $form_state, $context); which adds 'token_element_validate' to all text-based inputs.
• Add protected \Drupal\webform\WebformTokenManager::elementValidateRecursive($element, $form_state, $context); which will recursively add 'token_element_validate' to all text-based inputs.
• Apply WebformTokenManager::elementValidate() to all element, handler, setting, and configuration forms.
• Write a very basic test that confirms token validation is working correctly. This will require adding the token.module as a 'test_dependencies'

User interface changes

Token validation error message will appear if the token.module is installed and someone enters an invalid token.

Forms that now support with token validation.

/admin/structure/webform/config
/admin/structure/webform/config/submissions
/admin/structure/webform/config/handlers

API changes

None

Data model changes

None