When iterating on C test code, the Python fixtures that create disk
images run each time, even though the images have not changed. This
slows down the development cycle unnecessarily.
Add a -P/--persist option to prevent cleanup of test-generated files
like disk images. This allows re-running C tests directly, without
re-running the Python fixture each time.
Update the ext4l test to respect the persist flag.
Co-developed-by: Claude Opus 4.5 <noreply@anthropic.com>
Signed-off-by: Simon Glass <simon.glass@canonical.com>
bcfa556a36