These commits add some cleanup items requested by @alalazo on #51137.

I noticed that in 3.13, argparse actually added a deprecated=True option to arguments, but we can't use that yet since 3.13 is too new. I added a DeprecatedStoreTrueAction to spack.cmd.common.arguments here that we can use to deprecate arguments (and I suppose we can generalize it for other actions later). It does more than the deprecated=True, e.g.:

    # deprecated for the more generic --by-name, but still here until we can remove it
    subparser.add_argument(
        "--variants-by-name",
        dest="by_name",
        action=arguments.DeprecatedStoreTrueAction,
        help=argparse.SUPPRESS,
        removed_in="a future Spack release",
        instructions="use --by-name instead",
    )

and prints:

> spack info --variants-by-name
==> Warning: --variants-by-name is deprecated and will be removed in a future Spack release.
  use --by-name instead