Add export of groups and service principals with error handling

[FabienTschanz]

Pull Request (PR) description

This PR adds the ability to export groups and service principals as well instead of only users in AADEntitlementManagementRoleAssignment. It also fixes an issue where the Connected organization administrator role is unavailable. It is now hardcoded into the resource. A dynamic retrieval is not possible because if RoleDefinition is expanded, roles with the Connected organization administrator are not returned from the Graph API (because there is no definition to expand).

This Pull Request (PR) fixes the following issues

• Fixes AADEntitlementManagementRoleAssignment can fail due to incorrect scope and resulting roledefinitionId #5620
• Fixes AADEntitlementManagementRoleAssignment failing when assignment is to service principal #5618

Task list

• Added an entry to the change log under the Unreleased section of the file CHANGELOG.md.
  Entry should say what was changed and how that affects users (if applicable), and
  reference the issue being resolved (if applicable).
• Resource parameter descriptions added/updated in the schema.mof.
• Resource documentation added/updated in README.md.
• Resource settings.json file contains all required permissions.
• Examples appropriately added/updated.
• Unit tests added/updated.
• New/changed code adheres to DSC Community Style Guidelines.