Added skeleton class for PrivilegeAccess

Also added the skeleton of the tests for PrivilegeAccess
Conversion and Get/Lookup methods implemented for PrivilegeAccess

All tests pass
Refactored the extension methods

The previous `Contains` was updated to `SameAs` to more accurately
reflect the purpose of the function. The new `Contains` checks that the
value is in the source, without caring what else is in the source
Add method implemented for PrivilegeAccess

All tests pass
Delete method implemented for PrivilegeAccess

All tests pass