RetryHandler should add more information on failures

[andrueastman]

Sourced from microsoftgraph/msgraph-beta-sdk-dotnet#816

The default retry handler simply throws an InvalidOperationException exception when it reaches the maximum retry count. The error message is simply set to: «Too many retries performed.» and the inner exception simply states: «More than {retryCount} retries encountered while sending the request.»
There is no way to know why retries have been performed. What were the error codes and error messages?

The retry handler should return an AggregateException (or a specific exception like TooManyRetriesException) with one exception per retry specifying the HTTP status and the error code returned by the server.

[andrueastman]

This was resolved via #223