Add C implementations of filesystem tests that can be called via
the 'ut fs' command. These tests use UTF_MANUAL flag since they require
external setup, i.e. creation of filesystem images.
This covers the existing TestFsBasic tests.
The tests use typed arguments (fs_type, fs_image, md5 values) passed
via the command line.
Add a few helpers to make the code easier to read.
Co-developed-by: Claude <noreply@anthropic.com>
Signed-off-by: Simon Glass <simon.glass@canonical.com>