Augments colcon pkg with dependencies from pyproject file.

[francocipollone]

Related to #37

Summary

This PR introduces the ability to indicate the colcon/ros dependencies of the project via the pyproject.toml file.
Otherwise, dependencies for the package aren't loaded up, and the ordering when building isn't respected

Use

Add to pyproject.toml the following section:

[colcon-package]
depend = ["another_pkg_1"]   # This will add to both `build_depend` and `exec_depend` following `package.xml` standards
build_depend = ["another_pkg_2"]
exec_depend = ["another_pkg_3"]
test_depend = ["another_pkg_4"]

[velovix]

Thank you for doing this!

[francocipollone]

Thanks @velovix for the prompt review and merge and also for adding documentation I missed. 💯

Are you planning a patch/minor release shortly to incorporate these changes?