r2r rewrite in V

This is the full rewrite of the r2 regressions testsuite in the V programming language.

Reasons behind using V are:

• Go-like syntax: Easy to maintain and for newcomers
• Portability: Compiles to C with no dependencies
• Speed: Just use native apis instead of spawn all the things

The current testsuite is written in NodeJS and have some issues:

• Hard to architect structured js, ts helps, but its just layers on layers
• Some lost promises happen in travis which are hard to debug
• Simplify the testsuite to cleanup broken or badly written tests
• Have a single entrypoint to run ALL the tests (unit, fuzz, asm, ..)
• Latest versions of NodeJS don't run on net/open/free-BSD

Things to be done:

• Implement the interactive mode to fix failing tests
• Clone+build V if not in the $PATH

Stuff to improve:

• Proper error handling
• Timeouts without using rarun2
• Improve r2pipe.v performance

--pancake