Warn when client-specific options are used with exporter in login command

[raballew]

Original TODO comment:
# TODO: warn if used with exporter

Location: python/packages/jumpstarter-cli/jumpstarter_cli/login.py, line 128

Context:

@click.option("--name", type=str, help="Enter the Jumpstarter exporter name.", default=None)
@opt_oidc
# client specific
# TODO: warn if used with exporter
@click.option(
    "--allow",
    type=str,
    help="A comma-separated list of driver client packages to load.",
    default="",

The login command accepts client-specific options that are irrelevant when used in exporter mode. A warning should be emitted.