Peregrin: Refactoring the Runtime

[jakhog]

Summary

We have refactored a lot of the internals of the Runtime - to remove code that we no longer need, and to rely more on well tested frameworks over own code. Notable examples:

• The booting system is gone, we only discover DI container bindings and use the .NET hosting model for the rest
• The resources system is gone, and replaced with "normal" configuration. We don't need multiple implementations of the same resource types.
• The configuration system was replaced with the Microsoft Configuration system, which should make it easier to load configuration from multiple sources - and in the future support hot-reloading.
• The ExecutionContextManager that used AsyncLocal storage is gone, and we pass along the ExecutionContext explicitly or resolve dependencies from tenant-specific containers.
• Removed the custom DepenencyInjection setup, and replaced it with AutoFac and a tenant-specific child container structure that allows us to ensure we don't mix dependencies for different tenants.
• Upgraded from the native Grpc libraries to the C# Grpc libraries that uses AspNetCore (Kestrel) for hosting.

Added

• A HealthCheck endpoint is exposed on the "web" endpoint (defaults to 8001) on /healthz. This endpoint returns 200 if the configuration files are correctly formatted, the MongoDB databases are reachable and the gRPC services running. Otherwise it returns an error and a JSON structure describing the issues.
• The "web" endpoint port is configurable in the endpoints.json file.
• More metrics for ReverseCallDispatcher

Changed

• Change from the Grpc.Core native packages, to the Grpc.AspNetCore C# packages
• The Docker Images that are pushed to Docker Hub are now multi-architecture, supporting amd64 and arm64.

Fixed

• The RetryTime that was passed along from the SDKs when a Projection failed was not used, meaning that failing projections were never retried.
• Filters that failed to write the filtered event to the stream, threw an error propagated to the SDK instead of handling it as a filter failure and retrying later.
• ReverseCalls where the Connect arguments were invalid, caused the SDKs to receive a generic gRPC error instead of the failure that occurred in the Runtime.

Deprecated

• The -arm64 images on Docker Hub will no longer be released. The "normal" images should be used in place.