test/py: Add tests for the erofs

Add Python scripts to test 'ls' and 'load' commands, as well as
test related filesystem functions.

Signed-off-by: Huang Jianan <jnhuang95@gmail.com>
diff --git a/tools/docker/Dockerfile b/tools/docker/Dockerfile
index f1d597a..c51e343 100644
--- a/tools/docker/Dockerfile
+++ b/tools/docker/Dockerfile
@@ -48,6 +48,7 @@
 	dosfstools \
 	e2fsprogs \
 	efitools \
+	erofs-utils \
 	expect \
 	fakeroot \
 	flex \