Add gradle_module to plugin list expected output files

Add the gradle_module handler entry to the expected --list-packages
output files so that test_package_list_command passes. Also add
plugins_list.txt for macOS (non-Linux) test runs.

Signed-off-by: Devang Pratap Singh <devangpratapsingh@outlook.com>
Signed-off-by: devangpratap <115096812+devangpratap@users.noreply.github.com>

Author: devangpratap