Attach libraries to examples plugin definitions

Problem/Motivation

Instead of adding the attachment in the render array itself:

album:
  label: Bootstrap Album
  description: "Simple one-page template for photo galleries, portfolios, and more. https://getbootstrap.com/docs/4.6/examples/album/"
  render:
    - "#type": pattern
      "#id": jumbotron
      "#attached":
        "library":
          - ui_suite_bootstrap/album_example

Attach it to the definition, like what ui_patterns is already doing:

album:
  label: Bootstrap Album
  description: "Simple one-page template for photo galleries, portfolios, and more. https://getbootstrap.com/docs/4.6/examples/album/"
  render:
    - "#type": pattern
      "#id": jumbotron
  library:
   - ui_suite_bootstrap/album_example

It is flatter and cleaner.