Align entra group member commands

[milanholemans]

Currently we have 3 commands: entra group member add, entra group member set, entra group member list.

I've noticed that the command entra group member list has an option called groupName to reference the group you want to target. The two other commands have the option groupDisplayName.
Let's align these commands to improve consistency.

To-do:

• Deprecate option groupDisplayName for the add and set commands
  • Show a deprecation warning when people use this option.
• Introduce a new option --groupName [groupName]
• Update docs examples & command tests.