Provides default parameters for the RoadNetworkLoader.

[francocipollone]

🎉 New feature

Related to https://github.com/maliput/maliput/issues/531 Relies on https://github.com/maliput/maliput/pull/532

Summary

Implements the new method for providing default parameters via RoadNetworkLoader.

Checklist

• [x] Signed all commits for DCO
• [ ] Added tests
• [ ] Added example and/or tutorial
• [ ] Updated documentation (as needed)
• [ ] Updated migration guide (as needed)
• [ ] Consider updating Python bindings (if it affects the public API)

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

[agalbachicar]

Check CI please.

[francocipollone]

@ros-pull-request-builder retest this please

[francocipollone]

@ros-pull-request-builder retest this please