Update autoware_auto_create_pkg

Part of #462 (closed) (the important part).

To test:

ade enter
cd AutowareAuto
colcon build --merge-install --packages-up-to autoware_auto_create_pkg
colcon test --merge-install --packages-select autoware_auto_create_pkg
source install/setup.bash
ros2 run autoware_auto_create_pkg main.py --destination $(pwd)/src --pkg-name test_pkg --maintainer "Test Person" --email test@example.com --description "Test package."
colcon build --merge-install --packages-up-to test_pkg
colcon test --merge-install --packages-select test_pkg

The --merge-install is required because /opt/AutowareAuto/ is built with --merge-install. If this flag isn't used, the main.py function won't be able to find the template folder from which to copy the package template when building this way. Instead, if I designed the package to work without --merge-install, it wouldn't work correctly once it's part of the installed build in /opt/AutowareAuto.