qtopcua should use cmake config for open62541

open62541 in vcpkg has a cmake config and open62541 can be build against OpenSSL. The cmake module qtopcua vendors for open62541 does not carry that transitive linkage requirement. As such qtopcua should probably just use the cmake config from open62541 if it is available to correctly take care of transitive linkage requirements such as OpenSSL.