The ComboBox is now generic (both in the sense of TypeScript generics as
well as use in other areas as the show selector). It’s behaviour now
also aligns with te TagInput component.

We’ve decided to move the show selector into the navbar because the
selected show is the primary state of the dashboard from which almost
all other state is derived.

Apart from that we now have support for filtering the list based on
active and inactive shows (and possible other criteria in the future) as
it was suggested in #122.

This re-implements the auth store with pinia.

Other notable changes:
* the OIDC client configuration and setup is now part of
  separate module that can be included by the OIDC callback routes
  and ensures that we always use the same OIDC client configuration.
* Authorization headers for the steering and tank REST APIs are now
  set with an axios interceptor instead of specifying them for each
  API store action.

refs #127

Accessing the $parent should only be used in rare cases. Login session
handling is already implemented as part of the store, so there is no
need to use the App component as handler.

Notable changes:
 * Vue 2.6 to Vue 3 + compat migration.
 * Build system migration from vue-cli/webpack to Vite.
 * Application dependencies like bootstrap-vue, vue-router, vuex,
   or vue-toast-nofitication have been updated, if doing so was
   necessary or advisable for the Vue 3 migration.
 * Static file includes for the oidc-client in oidc_callback.html
   and oidc_callback_silentRenew.html have been removed in favor
   of automatic processing in the build system so that all assets
   are versioned and invalid cache hits are prevented.

Fixes #53 and #110.

vue always throws a render error, even if we include a test for user.steeringUser
before comparing user.steeringUser.is_superuser.

so we moved it to the js logic and use a separat modules array for superusers

* deactivate superuser entries for standard users
* consistent naming

Our linting config in package.json was:
```
    "extends": [
      "plugin:vue/essential",
      "eslint:recommended"
    ],
```

Now switching to "plugin:vue/recommended" and apply all auto-fixes