CMS-1742 Add type definitions for relationshipType_createOrUpdate in RemoteService.ts

Add strict typing for the parameter and result values of RemoteServiceInterface.relationshipType_createOrUpdate()

* Check the RpcHandler method in Java to find the exact values accepted and returned.
* Use optional types (optParam?: string) where appropriate.
* Avoid use of any as much as possible and use concrete types.
* Look at types of space_list() and space_get() for reference.
Merge pull request #266 from enonic/CMS-1742

CMS-1742 Add type definitions for relationshipType_createOrUpdate in Rem...