Add more properties to ClientContext and have the ClientTransport provide it

[gjcairo]

The ServerTransport provides the ServerContext, as it contains information that only the transport knows about (such as the remote peer's address).

For consistency and to allow the ClientContext to also hold some additional information (such as remote and local peer descriptions), this PR changes the ClientTransport protocol so that implementations also provide the corresponding ClientContext.

This PR also adds additional information to the context (which will be used by the tracing interceptor but can be useful for users in general): remote and local peer addresses, server hostname, and network transport.

[gjcairo]

The API breaks are expected, since we've added the ClientContext to the closure signature:

💔 API breakage: func ClientTransport.withStream(descriptor:options:_:) has parameter 2 type change from (GRPCCore.RPCStream<Self.Inbound, Self.Outbound>) async throws -> T to (GRPCCore.RPCStream<Self.Inbound, Self.Outbound>, GRPCCore.ClientContext) async throws -> T

💔 API breakage: constructor ClientContext.init(descriptor:) has been removed

💔 API breakage: func InProcessTransport.Client.withStream(descriptor:options:_:) has parameter 2 type change from (GRPCCore.RPCStream<GRPCInProcessTransport.InProcessTransport.Client.Inbound, GRPCInProcessTransport.InProcessTransport.Client.Outbound>) async throws -> T to (GRPCCore.RPCStream<GRPCInProcessTransport.InProcessTransport.Client.Inbound, GRPCInProcessTransport.InProcessTransport.Client.Outbound>, GRPCCore.ClientContext) async throws -> T

[glbrntt]

Fab, thanks Gus!