Create a python script to list files given a directory as an input

The script will be used in generating a file that lists generated stub
files from metalava, which will be passed to soong_zip to extract
selected stub files when generating stubs from java_api_library modules
with incomplete api surface text files.

Test: build java_api_library modules in aosp/2487335
Change-Id: I36b830f14c714315f81e3fd8608d84c29f673f83

tools/Android.bp

@@ -85,3 +85,11 @@ python_binary_host {
         "libprotobuf-python",
     ],
 }
+
+python_binary_host {
+    name: "list_files",
+    main: "list_files.py",
+    srcs: [
+        "list_files.py",
+    ],
+}