New features

• Support WriteAsync cancellation token (#1645)
• Reconnect backoff configuration (#1668)

Changes

• Log HTTP method when adding endpoint (#1637)
• WriteAsync on the server now throws on failure (#1645)
• WriteAsync on the client with hedging now waits for success before continuing (#1645)

Fixes

• Fix calls throw TaskCanceledException after previous call is canceled (#1664)
• Fix unobserved exception from failed calls (#1660)
• Fix dotnet-grpc error when additionalImportDirs is null (#1666)
• Fix not flushing buffered writes when client streaming and hedging (#1645)
• Fix race between server FlushAsync exiting and request cancellation token (#1645)