Feature direct backend

[nagendramishr]

Proxy:

• Added CheckingBackgroundRequestStatus and BackgroundRequestSubmitted as a status for background requests
• Fix bugs related to background request lifecycle
• Bug fixes for async processed request status updates
• Added support to connect to EventHub via managed identity
• Added configurable delay to wait for EventHub startup
• Refactor configuration startup to use reflection
• Update client library versions for Core, Identity, ServiceBus, BlobStorage and DI
• Minor perf improvement parsing headers
• Added consolidated AsyncSBConfig env var
• Added check for unauthorized access during startup
• Enhanced logging in debug level
• Make the SAS generation configurable in the user profile, default to off
• Added a blob worker queue to reduce resource contention
• Refactored code to utilize the blob workers
• Capture backend config errors
• Fix circuit breaker usage, add CB stats to health
• Streamline blob creation until needed
• Add AsyncTTLSecs as config parameter
• Improve performance of probe requests
• Capture error codes from inner exception on HttpException
• Don't read the body for probe queries to the backends
• Bug fix for null eventhub client
• Streamline memory used by event objects
• Add streamlined probe server with ability to run as side car
• Reworked ProxyWroker to match the response flow from the 2.1.x release
• Track HTTP response in proxy data and dispose after delivery to client