expose settings for channel-level compression

[generall]

related reference https://chromium.googlesource.com/external/github.com/grpc/grpc/+/HEAD/examples/python/compression/

[avirlrma]

Where would we want to expose this setting - at the client level or at per method level?

[joein]

At the client

[Merthoshan]

Can I get a little more detail as to what the problem is? I would like to work on it

[joein]

implemented in #480