medusa user CLI command create new member as member not as admin

[LWJerri]

Is your feature request related to a problem? Please describe.
When the user uses the medusa user -e example@example.com -p password CLI command medusa generates a new user as member, not as admin. I think it's can produce some problems in the future.

Describe the solution you'd like
I think we can edit create user option and set the default role as admin for the CLI command.

Also related to #2656