Standardize version manager script execution

[vinistock]

Motivation

Closes #2114.

We were not passing the process environment or the shell detected by VS Code to version manager activation scripts.

However, it's becoming more evident that many version managers depend on certain environment variables to properly work (e.g.: $HOME). In addition to that, Rubygems itself depends on certain environment variables in order to define what the default and user gem paths are.

I think it's worth trying to standardize these script executions to always use the user's selected shell (which some version managers depend on) and make the execution inherit from process.env.

Notice that we're still not sourcing shell configuration scripts, since we moved away from that due to several integration issues.

Implementation

Created a convenience method runScript which always inserts the cwd, env and shell. Started using it everywhere we invoke manager integrations.

Small detail: vscode.env.shell returns an empty string rather than null in operating systems where that value is not set to anything. We do not want to pass an empty string to exec, but rather undefined or null.

Automated Tests

Adapted our tests.

Manual Tests

Essentially, launch the extension on this branch and ensure the server boots properly.

[vinistock]

Since we now have the preview release available to us again, I'm going to ship one with this change to ensure we don't wreak havoc to activation with these changes.

[SeanSith]

Any chance of getting this sort of syntax to work in the next update?

  "rubyLsp.bundleGemfile": "$HOME/.config/vscode/Gemfile",

Results in

2024-06-07 12:12:46.586 [info] (selectbreeders) Running command: `. /opt/homebrew/opt/asdf/libexec/asdf.sh && asdf exec ruby -W0 -rjson -e 'STDERR.print({env: ENV.to_h,yjit:!!defined?(RubyVM::YJIT),version:RUBY_VERSION}.to_json)'` in /Users/seansith/code/[project name redacted]/$HOME/.config/vscode using shell: /bin/zsh