token_tree_link requires the token contrib module

Problem/Motivation

$form['token_label']['#markup'] = $this->t('This field supports tokens.');
    $form['token_link'] = [
      '#theme' => 'token_tree_link',
      '#token_types' => [$this->tokenType],
    ];

won't work without the token contrib module!

So it needs a dependency on token:token in the module file or a check for token module existence in code.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes