Auto-formatters can’t know if we rely on any special white-space
handling in our code, so they take the safe route and assume we do.

In this case we don’t, so we can apply formatting that looks a little
more sensible.

Some iteration semantics got mixed up when replacing remaining uses of
`var` variable declarations in ae37fb6c.

`var foo in bar` cannot be replaced with `const foo of bar` because the
first will assign the iteration index of the current item to foo,
whereas the second will assign the actual iteration item.

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

The show selection mechanism relied on the parent component to notify
other components, even though the selected show is already part of the
store and all component state can and should be derived from there.