With the recent qemu (d9a0fdda and
04269349) and zephyr
(05cad7b5

) changes to how their tests are
run, two things became unused:

- The tinytest framework, which embedded a set of tests and their expected
  output within firmware, so these tests could be run stand-alone.

- The `--write-exp` and `--list-tests` options to `tests/run-tests.py`,
  which were needed primarily to generated the expected test output for
  tinytest (also the associated `tests/run-tests-exp.py/.sh` scripts are
  now unused).

This commit removes the tinytest component and all its helper code.  This
eliminates a maintenance burden.

Signed-off-by: Damien George <damien@micropython.org>