Support getting enum metadata from a LabVIEW cluster

[pbirkhol-ni]

When using an enum message, grpc-labview requires you to register enum metadata. This works fine when generating a client/server using grpc-labview's code generator, but MeasurementLink doesn't do this. Instead, MeasurementLink uses Cluster to gRPC LabVIEW Message.vi to dynamically generate message metadata at runtime. This has always worked fine, but with grpc-labview 1.0.0.7, it no longer works with enums. The reason is that we now have to register enum metadata with grpc-labview.

One possible fix is to add a VI to generate the enum metadata given a cluster, similar to how Cluster to gRPC LabVIEW Message.vi works. Then MeasurmentLink would call that new VI and register the resulting metadata.

AB#2518465

[pbirkhol-ni]

I have verified in the latest release that this is fixed. The overall issue that measurementlink-labview is trying to solve is not yet fixed, but this issue as written has been verified.