Implement chdir emulation for rakudo.

Implemented chdir emulation in rakudo. Tested with both parrot and jvm backends.
Tested with panda, up to point of compilation failure, due to parrot specific compile command.
Tested on MacOS.
Needs tested on Windows.

t/spec/S32-io/IO-Socket-INET.t ........... ok
t/spec/S32-io/chdir.rakudo.jvm ........... ok
t/spec/S32-io/copy.t ..................... Failed 2/29 subtests
t/spec/S32-io/dir.t ...................... ok
t/spec/S32-io/file-tests.t ............... ok
t/spec/S32-io/io-handle.rakudo.jvm ....... ok
t/spec/S32-io/io-path-cygwin.rakudo.jvm .. ok
t/spec/S32-io/io-path-unix.rakudo.jvm .... ok
t/spec/S32-io/io-path-win.rakudo.jvm ..... Failed 19/51 subtests
t/spec/S32-io/io-path.t .................. ok
t/spec/S32-io/io-spec-cygwin.t ........... ok
t/spec/S32-io/io-spec-unix.t ............. ok
t/spec/S32-io/io-spec-win.t .............. Failed 33/206 subtests
t/spec/S32-io/note.rakudo.jvm ............ Failed 5/6 subtests
t/spec/S32-io/path.t ..................... No subtests run
t/spec/S32-io/slurp.t .................... ok
t/spec/S32-io/spurt.t .................... Failed 1/24 subtests