Enable tag filtering within MapGrpcHealthChecksService()

Is your feature request related to a problem? Please describe.

While Add[Async]Check() allows for specification of tags to then filter for them via MapHealthChecks()'s HealthCheckOptions.Predicate for HTTP GET requests, there’s no such support via MapGrpcHealthChecksService().

Describe the solution you’d like

I’d like to filter for tags via something like that mentioned Predicate property mechanism in MapGrpcHealthChecksService(), too.

Describe alternatives you’ve considered

• Implementing an overloaded method - not really an option.
• Using GrpcServiceEndpointConventionBuilder’s Add() method - failed to do so due to lack of documentation on how to use that convention builder correctly for my purpose.

Additional context

I’d like to use that filtering mechanism to separate between an AddDbContextCheck() readiness probe & another one for a liveness probe.

[JamesNK]

Btw I rewrote the PR and made some major changes. It now supports mapping health results to service names. It makes it easier to aggregate multiple health checks together.

[JamesNK]

I took a look at this. Does https://github.com/grpc/grpc-dotnet/pull/1565 let you achieve what you want?