Add separate module handling for PowerShell Core

[FabienTschanz]

Pull Request (PR) description

This PR removes the dependency that all PowerShell modules need to be installed under C:\Program Files\WindowsPowerShell\Modules* and massively improves the installation speed if the Microsoft.PowerShell.PSResourceGet module is installed. This module is installed by default if run from PowerShell 7.4 or greater.

The improvement is inspired from issue #5433 and from my own experience with PowerShell 7. Microsoft365DSC seems to run fine with PowerShell 7, and now it doesn't require a hard dependency on any module except PnP.PowerShell to be installed under Windows PowerShell 5.1.

This Pull Request (PR) fixes the following issues

None.

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.