[Module Proposal]: `avm/res/authorization/role-assignments/rg-scope`

### Check for previous/existing GitHub issues/module proposals

- [x] I have checked for previous/existing GitHub issues/module proposals.

### Check this module doesn't already exist in the module indexes

- [x] I have checked for that this module doesn't already exist in the module indexes.

### Bicep or Terraform?

Bicep

### Module Classification?

Resource Module

### Module Name

avm/res/authorization/role-assignments/rg-scope

### Module Details

I find myself doing this in a few places:
```bicep
import { roleAssignmentType } from 'br/public:avm/utl/types/avm-common-types:0.7.0'
param resourceGroupRoleAssignments roleAssignmentType[]?

module resourceGroupRoleAssignment 'br/public:avm/res/authorization/role-assignment/rg-scope:0.1.1' = [
for (roleAssignment, index) in resourceGroupRoleAssignments ?? []: {
name: 'resourceGroupRoleAssignment-${index}'
params: {
roleDefinitionIdOrName: roleAssignment.roleDefinitionIdOrName
principalId: roleAssignment.principalId
description: roleAssignment.?description
principalType: roleAssignment.?principalType
condition: roleAssignment.?condition
conditionVersion: roleAssignment.?conditionVersion
delegatedManagedIdentityResourceId: roleAssignment.?delegatedManagedIdentityResourceId
}
}
]
```

It would be nice if there was a version that takes a roleAssignmentType[] directly.:
```bicep
import { roleAssignmentType } from 'br/public:avm/utl/types/avm-common-types:0.7.0'
param resourceGroupRoleAssignments roleAssignmentType[]?

module resourceGroupRoleAssignment 'br/public:avm/res/authorization/role-assignments/rg-scope:x.y.z' = {
params: {
roleAssignmentType: resourceGroupRoleAssignments
}
}
```

### Do you want to be the owner of this module?

No

### Module Owner's GitHub Username (handle)

_No response_

### (Optional) Secondary Module Owner's GitHub Username (handle)

_No response_

Start by inspecting the existing br/public:avm/res/authorization/role-assignment/rg-scope:0.1.1 module and the AVM module indexes. Confirm the conventions for resource modules and roleAssignmentType, then define the new role-assignments/rg-scope module so it accepts the array directly and verify it is published and indexed as requested.

Written by the indexing model from the issue text.