Add TruffleRuby in CI

[eregon]

It would be nice if benchmarks also ran a single iteration on TruffleRuby in CI.
Currently all benchmarks pass after #250

If some new benchmark does not work on truffleruby or there is some issue with a benchmark on truffleruby it would be fine to just exclude that benchmark on truffleruby, the goal is not to prevent merging benchmarks which do not work on truffleruby but just raise awareness if a change to yjit-bench does not work on TruffleRuby.

[eregon]

Actually I think it'd be good to test on the latest CRuby release too, to make sure benchmark run fine there too, I pushed a commit for that.

[noahgibbs]

Currently failing for TruffleRuby in CI due to a StackOverflowError, looks like a line that calls itself:

from org.truffleruby.language.methods.TranslateExceptionNodeGen.executeTranslation(TranslateExceptionNodeGen.java:112)
	from org.truffleruby.language.RubyMethodRootNode.execute(RubyMethodRootNode.java:99)
/home/runner/.rubies/truffleruby-head/lib/gems/bundler/gems/rails-4e01a7e8753c/activesupport/lib/active_support/descendants_tracker.rb:60:in `subclasses'
	from /home/runner/.rubies/truffleruby-head/lib/gems/bundler/gems/rails-4e01a7e8753c/activesupport/lib/active_support/descendants_tracker.rb:61:in `subclasses'
	from /home/runner/.rubies/truffleruby-head/lib/gems/bundler/gems/rails-4e01a7e8753c/activesupport/lib/active_support/descendants_tracker.rb:61:in `subclasses'
	from /home/runner/.rubies/truffleruby-head/lib/gems/bundler/gems/rails-4e01a7e8753c/activesupport/lib/active_support/descendants_tracker.rb:61:in `subclasses'
	from /home/runner/.rubies/truffleruby-head/lib/gems/bundler/gems/rails-4e01a7e8753c/activesupport/lib/active_support/descendants_tracker.rb:61:in `subclasses'
	from /home/runner/.rubies/truffleruby-head/lib/gems/bundler/gems/rails-4e01a7e8753c/activesupport/lib/active_support/descendants_tracker.rb:61:in `subclasses'
	from /home/runner/.rubies/truffleruby-head/lib/gems/bundler/gems/rails-4e01a7e8753c/activesupport/lib/active_support/descendants_tracker.rb:61:in `subclasses'

[eregon]

Yes, that's fixed by #250, I didn't include these commits again here to make the diff easier to review. Will rebase once that's merged.

[eregon]

cc @k0kubun ruby test/*_test.rb only works with a single file, with more files the 2nd and later files would just be user arguments, so I changed to this for clarity.