test/py: Add tests for the SquashFS commands

Add Python scripts to test 'ls' and 'load' commands. The scripts
generate a SquashFS image and clean the directory after the assertions,
or if an exception is raised.

Signed-off-by: Joao Marcos Costa <joaomarcos.costa@bootlin.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index 8ec6c5d..b12074f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -975,6 +975,7 @@
 F:	fs/squashfs/
 F:	include/sqfs.h
 F:	cmd/sqfs.c
+F:	test/py/tests/test_fs/test_squashfs/
 
 TARGET_BCMNS3
 M:	Bharat Gooty <bharat.gooty@broadcom.com>