support/testing: micropython: add micropython-lib test

Commit 8f403f0 "package/micropython-lib: merge with, and install
as part of micropython" brought micropython library within the
package.

This commit improves the micropython runtime test by enabling the
micropython-lib and by also adding a runtime test using one of its
module. We choose to use the gzip module, and check whther decodign q
simple gziped file works; the micropython-lib gzip can only decompress,
so we need to prepare it from the shell.

Signed-off-by: Julien Olivain <ju.o@free.fr>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

support/testing/tests/package/test_micropython/rootfs-overlay/root/zcat.py

@@ -0,0 +1,15 @@
+#! /usr/bin/env micropython
+
+import gzip
+import sys
+
+
+def main(fname):
+    with open(fname, "rb") as f:
+        with gzip.GzipFile(fileobj=f) as g:
+            s = g.read()
+            print(s.decode("UTF-8"), end="")
+
+
+if __name__ == "__main__":
+    main(sys.argv[1])