Creates a child test object of this test object.
This operation does not cause LeanFT to search for the object in the AUT. LeanFT interacts with the application only when a step runs that performs an operation on the AUT object.
TChild - the generic type of the child test object.
type - the test object interface type.
description - a Description containing the set of properties and values that uniquely identify this object in the AUT.
The new child test object with the provided description.