This operation returns a top level TL given its name.

Operation Exceptions:
1. INTERNAL_ERROR - Raised in case of non-specific OS internal failure.
2. NOT_IMPLEMENTED - Raised when the OS does not support this operation.
3. INVALID_INPUT - Raised when topoLinkName does not reference a top-level topological link object.
4. ENTITY_NOT_FOUND - Raised when topoLinkName references a top-level topological link object that does not exist.
