feat: add the ability to define env variables for use when debugging

[Alanoll]

This adds the ability to define a separate set of environment variables to use when debugging vs when normal running of the tests via the extension.

A new vitest.debugNodeEnv setting is added to the extension and only used when executing a test via debugging.

[Alanoll]

I wasn't sure where/how to add tests that explicitly test with the debugger in play, so I modified an existing test project that had tests for environment variables.

[sheremet-va]

LGTM 👍