[tutorials] Highlight remote (http) PackageMap capability more prominently

[jwnimmer-tri]

In #9498 we added AddRemote feature to PackageMap but it seems many people don't know about it, or don't easily find it, or can't figure out how to use it.

To make everything more clear, perhaps we should add a demo as part of the authoring_multibody_simulation.ipynb tutorial.

Perhaps loading one of the dm_control models would be a good demo.

[RussTedrake]

in the mean time, here is a simple example of pulling from git

    parser.package_map().AddRemote(
        package_name="gcs",
        params=PackageMap.RemoteParams(
            urls=[
                f"https://github.com/mpetersen94/gcs/archive/refs/tags/arxiv_paper_version.tar.gz"
            ],
            sha256=("6dd5e841c8228561b6d622f592359c36517cd3c3d5e1d3e04df74b2f5435680c"),
            strip_prefix="gcs-arxiv_paper_version",
        ),
    )