Makes relative paths work correctly.

To make installing as a PWA possible. Fixes #1181.

Was looking a bit janky with the style changes.

If you want to use the last visited directory you should omit the
directory from the command line.

Fixes #1132.

Instead of the first.

- Add VS Code icon
- Trim dashboard to just display dedicated VS Code section
- Version was getting unset during build
- Add back nbin shim which I temporarily took out earlier
- Update tests for log level env var changes

Also add a way to force a check.

Just a login form and a list of applications. No modals or anything like
that.

Now it should work whether you have a trailing slash or not.

Reworked from d5740128 to fit in the
new structure.

Otherwise there is risk of an infinite loop through the iframe where the
fallback keeps loading the root HTML which itself has an iframe...

This is mostly for development where VS Code might not have finished
compiling yet.