### 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.
VARIABLES_COMMANDS = (
    ActionCommand(
        name="list",
        help="List variables",
        func=lazy_load_command("airflow.cli.commands.variable_command.variables_list"),
        args=(ARG_OUTPUT, ARG_VERBOSE),
    ),
    ActionCommand(
        name="get",
        help="Get variable",
        func=lazy_load_command("airflow.cli.commands.variable_command.variables_get"),
        args=(ARG_VAR, ARG_DESERIALIZE_JSON, ARG_DEFAULT, ARG_VERBOSE),
    ),
    ActionCommand(
        name="set",
        help="Set variable",
        func=lazy_load_command("airflow.cli.commands.variable_command.variables_set"),
        args=(ARG_VAR, ARG_VAR_VALUE, ARG_SERIALIZE_JSON, ARG_VERBOSE),
    ),
    ActionCommand(
        name="delete",
        help="Delete variable",
        func=lazy_load_command("airflow.cli.commands.variable_command.variables_delete"),
        args=(ARG_VAR, ARG_VERBOSE),
    ),
    ActionCommand(
        name="import",
        help="Import variables",
        func=lazy_load_command("airflow.cli.commands.variable_command.variables_import"),
        args=(ARG_VAR_IMPORT, ARG_VAR_ACTION_ON_EXISTING_KEY, ARG_VERBOSE),