Add default Ensure value if not present

[FabienTschanz]

Pull Request (PR) description

This PR adds the default Ensure property value Present if it is not specified in the desired values and the resource is not a single instance element.

This Pull Request (PR) fixes the following issues

• Fixes Resources using Test-M365DSCParameterState do not support default Ensure value when using -DesiredValues $PSBoundParameters #5085

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.

[FabienTschanz]

@Borgquite Do you have the time to test it with your usecase?