Support latest versions of rubyfmt

[wadetandy]

Your environment

• vscode-ruby version: 0.27.0
• Ruby version: any
• Ruby version manager (if any): rvm
• VS Code version: 1.45.1
• Operating System: OSX
• Using language server? yes

Expected behavior

I have installed the latest version of rubyfmt per the readme instructions, so it is available on my bash PATH as rubyfmt. I would expect this command to get run when the vscode formatter runs.

Actual behavior

Per this file, vscode-ruby embeds a much older version of rubyfmt, which the author notes as broken in fables-tales/rubyfmt#201.

[wingrunr21]

I haven't looked at rubyfmt in a while. It looks like it is getting transitioned to something I shouldn't vendor any longer. I'll have to do some work to redo the integration to allow it to be external similar to other formatters.

[wadetandy]

@wingrunr21 Opened #628 to address this change.

[wingrunr21]

v0.28.0 contains this support