Restore debugging support via ruby/debug

[chadlwilson]

Debugging support was dropped in 0.7.0 of the plugin via #292 due to lack of ability to reliably install ruby-debug-ide and debase across various OSes and Ruby versions 3.0+ while building native extensions from Ruby source. The last versions these gems seem to reliably install on across OSes is Ruby 2.7.

Due to low awareness of how frequently the debugging support for Ruby is used, it has been dropped.

To add it back it would probably be required to

• review why/how it was removed in 7c7bbae
• re-implement on top of https://github.com/ruby/debug which is both maintained and designed for modern rubies
• investigate how to make things work via gauge's IDE support (and possibly rdbg for VSCode?)