Disable RVM nag warning about a Ruby version not being installed #690

The Codespaces and Ruby images include rvm and rbenv for convienence, but rvm triggers warnings if a Gemfile is found that references a Ruby version, even if the system version matches it.

Its worth investigating if we can remove this warning rvm rvmrc warning ignore allGemfiles alone doesn't seem to do it for some reason.

//cc: John Keech (@jkeech)