Adds support for channel, peer, and connection draining.
Introduces lazy relaying, allowing Hyperbahn to read and write small parts of
protocol frames without creating and collecting unnecessary complete request
and response object graphs. This feature is deployed experimentally and
enabled by a flag.
as=thrift
Supports Meta::health and Meta::thriftIDL endpoints for
TChannelAsThrift.
Surfaces TchannelAsThrift#waitForIdentified to consumers.