Refactor AspNetCore and WorkerService use of Heartbeat (DiagnosticTelemetryModule)

[TimothyMothra]

Currently, AspNetCore uses DependencyInjection for configuration for all components except the DiagnosticTelemetryModule which still depends on TelemetryConfiguration.Active.
This dependency is because of the Heartbeat feature.
The other TelemetryModules (AppServicesHeartbeatTelemetryModule and AzureInstanceMetadataTelemetryModule) don't do any real work and use .Active to apply their settings to the Heartbeat manager in the DiagnosticTelemetryModule.
In order to remove AspNetCore's dependency on .Active, the internal configuration will need to correctly configure these Modules using DI.

IMPORTANT: We've been recommending customers use DI to manually configure Heartbeat and DiagnosticTelemetryModule.

services.AddSingleton<ITelemetryModule>(new DiagnosticTelemetryModule());

We will continue to support this scenario.

The end goal is to support Heartbeat in all supported app models: Asp.Net, Asp.Net Core, and Worker-Service.