Use nuxt-layers for easy frontend component distribution

Motivation

Various functionality needs additonal vue components to work. For example, Drupal CMS integration needs vue-components for that, or a some frontend-admin-menu also.

By allowing the optional addition of layers the layers could add or even overwrite lots of frontend functionality on a flexible basis. It can do that without replacing the main frontend repository + it allows re-using the layers in projects when desirable as well.

Proposed resolution

Optionally add a nuxt-layer to the gitpod setup when an environment variable is set (via URL parameter).

E.g. the optional variable FRONTEND_NUXT_LAYER=github:StirStudios/stir_nuxt_base#release/nuxt-ui-lupus could add the respective nuxt-layer to a nuxt-based frontend.