Users should always be able to add new shows even if none have been
created thus far.

refs #97

Up until now we had two different show selectors based on the number of
shows that were available. We now use the same show selector for any
number of shows.

Apart from that shows are now sorted
 1. based on their active state (descending, so inactive last) and
 2. their name (ascending, so A-Z)
in the show selector so it’s easier to find relevant shows.

Other changes:
* title handling has been moved into PageHeader component
* calendar management has been removed and is now handled
  locally in the EmissionManager component
* inactive shows are badged

refs #122

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.

there have been issues with filenames that include spaces or other
characters. this is solved by double URL encoding.

for details see the migration guide for v2.0.0:
https://github.com/bootstrap-vue/bootstrap-vue/releases/tag/v2.0.0

also uses a b-table instead of b-rows because they are easy to rerender
after changes to the playlist entries array

New linter rules:
* curly
* block-spacing
* keyword-spacing

Also apply all autofixes introduced by these rules