Integrate with Channel?

[lann]

Some libraries want an actual Channel: https://docs.rs/opentelemetry-otlp/latest/opentelemetry_otlp/trait.WithTonicConfig.html#tymethod.with_channel

It seems at least plausible: https://docs.rs/tonic/0.13.1/tonic/transport/channel/struct.Channel.html#method.new