### Body

The CLI:

`airflow variables set [-h] [-j] [-v] key VALUE`

https://airflow.apache.org/docs/apache-airflow/stable/cli-and-env-variables-ref.html#set_repeat1

Doesn't support adding description though column exists and we support it from Rest API:
https://airflow.apache.org/docs/apache-airflow/stable/stable-rest-api-ref.html#operation/post_variables

**The Task:**

Allow to set description from cli command

### Committer

- [X] I acknowledge that I am a maintainer/committer of the Apache Airflow project.
choices=["sync", "eventlet", "gevent", "tornado"],
    help="The worker class to use for Gunicorn",
)
ARG_INTERNAL_API_WORKER_TIMEOUT = Arg(
    ("-t", "--worker-timeout"),
    default=120,
    type=int,
    help="The timeout for waiting on Internal API workers",
)
ARG_INTERNAL_API_HOSTNAME = Arg(
    ("-H", "--hostname"),
    default="0.0.0.0",
    help="Set the hostname on which to run the web server",
)
ARG_INTERNAL_API_ACCESS_LOGFILE = Arg(
    ("-A", "--access-logfile"),
    help="The logfile to store the access log. Use '-' to print to stdout",
)
ARG_INTERNAL_API_ERROR_LOGFILE = Arg(
    ("-E", "--error-logfile"),
    help="The logfile to store the error log. Use '-' to print to stderr",
)
ARG_INTERNAL_API_ACCESS_LOGFORMAT = Arg(
    ("-L", "--access-logformat"),
    help="The access log format for gunicorn logs",
)
ARG_NUM_RUNS = Arg(
    ("-n", "--num-runs"),
    default=conf.getint("scheduler", "num_runs"),
    type=int,