Allow for use of Bootstrap "Floating labels" on Drupal form elements

Screenshot of regular textfield and textfield with floating label:

Screenshot of regular textfield and textfield with floating label in focus:

Code is

    $form['text'] = [
      '#type' => 'textfield',
      '#title' => 'Textfield',
    ];

    $form['text_float'] = [
      '#type' => 'textfield',
      '#title' => 'Textfield',
      '#attributes' => [
        'placeholder' => 'Password',
        'floating_label' => 1
      ]
    ];

This will possibly conflict with some other MRs I have created, because of using preprocess_form_element and preprocess_input in these MRs too. If acceptable the MRs would need to be processed on after another and need to be rerolled.