Allow multiple templates per component

[grahl]

Components should allow to trigger different templates, instead of only one, e.g. searchbox.html.twig (default) searchbox-blue.html.twig (variant)

Possibly related to #2 Related Drupal integration issue: https://github.com/namics/drupal-twig-nitro-bridge/issues/1

[orlandothoeny]

Requires changing the Twig Loader to load templates according to these directory patterns:

• https://github.com/namics/generator-nitro/blob/develop/packages/project-nitro-twig/project/docs/nitro.md#render-pattern-elements
• https://github.com/namics/generator-nitro/blob/develop/packages/project-nitro-twig/project/docs/nitro.md#render-patterns

  // Component
  ${COMPONENT_NAME}/${COMPONENT_NAME}.twig
  // Element
  ${PARENT_COMPONENT_NAME}/elements/${COMPONENT_NAME}.twig
  // Component call with other template/variant
  ${COMPONENT_NAME}/${COMPONENT_NAME_TEMPLATE}.twig

This is required because it is possible that for component templates multiple .twig files with the same name exist. E.g. directory structure:

- atoms
  - link
    - link.twig
    - fancy.twig
  - text
    - text.twig
    - fancy.twig