[Feature request] Add Rakudo (former PERL6 ! ;) ) support

**Is your feature request related to a problem? Please describe.**
Cannot run scripts with the ```*.raku``` extension.

**Describe the solution you'd like**
Whatever was PERL6 decades ago, is Rakudo now.
Please support *.raku and *.rk and similar [file extensions of the Rakudo prog. language](https://docs.raku.org/language/filename-extensions)

THANKS!

No source file or test is named in the issue. Start by searching the TypeScript VS Code extension for existing language-to-command mappings and Perl-related support, then check how filename extensions are registered. Done means Rakudo scripts with .raku, .rk, and the relevant documented extensions can be run.

Written by the indexing model from the issue text.