Use maliput::test_utilities and try same branch name in actions

[scpeters]

This is a companion to maliput/maliput#368 (use updated target name maliput::test_utilities). As can be seen in the workflow result for commit 300e101, the workflow fails when compiled against the master branch of maliput, so I've also added support for checking out matching branch names of package dependencies in GitHub actions workflows, as discussed in maliput/maliput_infrastructure#136 (comment). The code linked in that comment is added to the try_vcs_checkout script, and there are two additional changes needed:

1. Set fetch-depth: 0 in actions/checkout steps for dependencies so that the fell git history is checked out (only needed for dependencies, not for checking out its own code since that is already on the proper branch).

2. Ensure that git 2.18+ is installed on the system before the actions/checkout steps are run. On 18.04, the standard version of git is 2.17, so we use the git-core ppa to install a newer version (currently 2.29). In anticipation of 20.04, which has git 2.25, I've moved the setup-ros step to the beginning, so that it alone can be used to install git when we switch to 20.04, and the ppa step can be removed.

Once this code has been reviewed and approved, I will open matching pull requests on on the other needed repositories.

[scpeters]

figuring out which branch to check out is a little tricky, since the GITHUB_REF is useful for push events if you strip the refs/heads/ prefix, but it is not useful in pull requests because it looks like refs/pull/18/merge. For pull requests, the GITHUB_HEAD_REF variable can be used, but this variable is blank for push workflows. With bash parameter substitution, I've used the following expression to use GITHUB_HEAD_REF if it is not empty, and otherwise use GITHUB_REF with refs/heads/ stripped from it:

• ${GITHUB_HEAD_REF:-${GITHUB_REF#refs/heads/}}

[francocipollone]

Nicely done!

[agalbachicar]

LGTM