Add Arch Linux support (and some auto code reformatting)

[mathgeniuszach]

This pull request fundamentally changes how paths are created to make it possible to work with Arch Linux out of the box without any configuration. On Linux, it's not guaranteed that all the sonic-pi content will be in a single app folder, so I separated paths to make it slightly more flexible to configure where certain files are, as absolute or relative paths.

I've only tested this with Arch with the community/sonic-pi package installed. If someone with a debian based machine can figure out where the sonic-pi bin folder is (it has the sonic-pi-server.rb file in it), where the theme folder is (it has a file called app.qss in it), and where the samples folder is (filled with .flac files), then feel free to mention it on issue #5 and I'll add it in or feel free to pull request it yourself.

I also did some formatting changes and made it so the sonic pi server will stop when you close/reload vscode.

[llloret]

Hey, @XMgzx, thank you for the PR. As you say, let's see if someone can check on another distro. Sadly, at the moment, I do not have the bandwidth to test it myself :(