Add Quokka configuration option to set `process.cwd()`

[smcenlly]

From @marcoSven via our discord channel:

What I would like is to use a relative path within a project. So in this example https://gitlab.com/marcoSven/quokka, the relative path './quokka.txt' should work if I only open the quokka.js file (no projects/no directories open), the src directory, or the root directory in a Sublime Text window.

Currently the relative path './quokka.txt' does not work when you open the root directory - in other words allow process.cwd() to be equal __dirname.

[smcenlly]

You should be able to use __dirname as a workaround to needing process.cwd() to be customized.

[marcoSven]

Thank you @smcenlly yes I am using this as a workaround for now, but using the javascript file location as root just makes more sense to me, so that a relative path always works. A configuration, if not default would be great.