CMS-1743 Add type definitions for relationshipType_delete in RemoteServi...

...ce.ts

Add strict typing for the parameter and result values of RemoteServiceInterface.relationshipType_delete()

 * 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.