[Modules] Simplify roleAssignment implementation for Resource Group

[MariusStorhaug]

Description

Simplify the inputs required for RG RBAC. As the resource ID is already provided in the scope of the deployment, the default is to get the current resourceGroup id.

Pipeline references

Pipeline

Type of Change

Please delete options that are not relevant.

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Update to documentation

Checklist

• I'm sure there are no other open Pull Requests for the same update/change
• My corresponding pipelines / checks run clean and green without any errors or warnings
• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (readme)
• I did format my code