Re-export all crates that have types present in our public API

[plafer]

For example, our public API requires ibc_proto::google::protobuf::Any. We should thus re-export ibc_proto in our lib.rs.

This will have many benefits:

1. When users upgrade their ibc-rs dependency (not through cargo update), it will just work, as opposed to showing a bunch of errors which effectively mean "upgrade ibc-proto as well".
2. It will make the ClientState derive macro (implemented in Static ClientState API #683) slightly cleaner (i.e. users will be allowed to rename their ibc_proto without breaking the macro).