Add collation tests, testing with $*COLLATION
Add collation tests, testing with $*COLLATION

Should add tests to close RT#132216 along with others. Added tag
[6.d-REVIEW] in a comment, since it should be reviewed before
a 6.d branch is created.

perl6/roast,dogbert17/roast,dogbert17/roast,bitrauser/roast,bitrauser/roast