Prerequisites

• I am using the latest version of Locust
• I am suggesting a new feature, not asking a question

Description

Introduction

In my team we would like to execute tests for many services at a time from the same script.
So it would be really helpful to be able to have a Select with all our services as "choices", and be able to select a subset of them depending on our needs.

Describe the solution you'd like

I'd like to specify a parameter "is_multiple" when defining a custom argument, so it would be passed to the Select form component. For example:

@events.init_command_line_parser.add_listener
def _(parser):
    parser.add_argument("--endpoints", choices=["status", "test", "users"], is_multiple=True, default=["status"], help="Endpoints")

Describe alternatives you've considered

The "ugly" option would be having a string argument and passing a comma-separated list of my selected services which then I would handle in the script.
Or having one checkbox option for each service and selecting them as necessary, which might be a bit better but still not the most elegant solution.

Additional context

I'm already working on a PR in case you think this feature makes sense.