Add ext4l_rename() to rename files and directories, including moves
across directories. This uses the Linux ext4_rename() function.
Also fix the symlink test to verify reading through symlinks works
correctly, since ext4l_resolve_path follows symlinks (stat behavior).
Add Python test wrappers for mkdir, ln, and rename tests.
Co-developed-by: Claude <noreply@anthropic.com>
Signed-off-by: Simon Glass <simon.glass@canonical.com>
da2593e6b0