Move dependency and version processing to augmentation

[cottsay]

In other colcon packages, the augmentation phase is responsible for adding this information. Two reasons this is a good idea:

1. This information isn't part of a package 'identity'
2. This allows a user to specify the package type in a colcon.pkg file and still get the dependency information parsed correctly.

For example, here's the augmentation logic for python packages for reading dependencies: https://github.com/colcon/colcon-core/blob/7b70e61175ab735ea5448ab6e88b4882975566b5/colcon_core/package_augmentation/python.py#L53-L55