Investigate how to support version managers that do not setup gem executables

[vinistock]

During RubyConf, I paired with someone using direnv + nix to manage Ruby and Bundler to install gems. The direnv + nix combo doesn't allow gem executables to be invoked, despite installing gems successfully. Even in this person's terminal, invoking gem executables was not possible.

The problem is even more complex because Bundler was configured to install gems in vendor/bundle and the developer had no idea where gems installed via gem install end up.

I'm wondering if we can instead force the installation path for the Ruby LSP to be inside the VS Code storage paths and then we launch the executable from there. It might make launch more robust for these scenarios.