Allow opening files in Nova editor

[goulvench]

Closes #518

Once this is merged, the wiki needs to be updated to indicate that Nova is now supported.

Remove…

### Panic Nova
Nova does not currently support opening files through a nova:// scheme URL.

Add…

## Panic Nova

Open Nova > Preferences… then click on the "Tools" button.
Under "Command Line Tool", click "Install" to install the command-line tool.

Add the following to your shell config:

export EDITOR="nova"

The URL is nova://open?path=%{file}&line=%{line}.
```

[AnalyzePlatypus]

Another Nova user here.
it wold be great if this could be merged.

Thanks!

[goulvench]

👋 @RobinDaugherty, merging this would be really useful for Nova users. Let me know if something's blocking merge and I'll fix it right away.

[goulvench]

I was using my branch in a Rails app but BetterErrors started complaining about missing sassc dependency when I updated to Rails 7 with Propshaft.

Setting export BETTER_ERRORS_EDITOR_URL="nova://open?path=%{file}&line=%{line}" in my editor works though, which is great. Copy and paste this into your terminal if you're lazy:

echo "export BETTER_ERRORS_EDITOR_URL=\"nova://open?path=%{file}&line=%{line}\"" >> ~/.bash_profile