This change implements a show overview page with two display modes:
table and grid. Shows can be ordered and searched. Other filters are not
(yet) implemented.

refs #101
refs #181

The AddShowButton was not rendered when the shows weren’t loaded, but
the only requirement for it to render should be if the user is a
superuser.

This component implements the logic for the standard
django-rest-framework (DRF) order parameter.

DRF uses plan field names for ascending and a "-" prefix for descending
order.

Example:
	if you’d want to sort by id you’d write:
		?order=id
	if you’d want to sort by id in reverse order you’d write:
		?order=-id

The OrderFilter supports arbitrary order fields, allows you to set the
sort direction (ascending, descending – configurable per order field)
and supports re-ordering of order fields so that that hierarchical
orders can be set.

This is a helpful ADialog wrapper that manages it’s open state by
itself.

This should make the API functions more accessible for callers as there
won’t be any loose undefined values that were sometimes needed to skip
certain values in certain API endpoints.

Instead, every positional argument is now required and all configurable
options or extensions are part of the options object.

refs #179

refs #179

Sometimes we don’t have a static list of choices but an async source for
them (like an API endpoint). This is now supported out of the box
through the searchProvider prop.

refs #185

refs #185

Bootstrap only displays form group errors if the .invalid-feedback
element is preceded by a .is-invalid element. That is an uncessary
restriction and we can simply enforce the errors to be displayed if it
is rendered.

refs #181

Pinia store destructuring doesn’t work on the plain store object. One
has to use storeToRefs or keep the original store object.

see: https://pinia.vuejs.org/core-concepts/

internal note and show owners are both admin-controlled.