Respect DAPR_GRPC_PORT environment variable if set externally, allow app-port to be suppressed

[badgeratu]

Description

Its now possible to define the environment variable DAPR_GRPC_PORT externally and Sidekick will use it to override the auto-calculated port for the sidecar. This allows the Workflow client to use the same port as the Sidecar. Note that it will also override any defined port in appsettings.json, this is in keeping with the way ASP.NET Core default builder configurations work.

Additionally as a pure-workflow application does not need to expose an AppPort, the HasAppPort option has been added to allow the app-port command-line option to be suppressed.

To verify this operation the WorkflowConsole sample from the Dapr dotnet-sdk has been added to the solution, and demonstrates the expected operation.

Finally the CheckHealthAsync() method has been added to IDaprProcessHost, so that IDaprSidecarHost can be used to check the sidecar health/availability on startup in a similar way to how DaprClient would be used.

Issue reference

#66

Please reference the issue this PR will close: #[issue number]

Checklist

Please make sure you've completed the relevant tasks for this PR, out of the following list:

• Code compiles correctly
• Created/updated tests
• Extended the documentation where possible