[Chronik] Move compiled proto module from chronik-http into new crate chronik-proto

Summary: This allows any crate to use protobuf structs, not just chronik-http.

Test Plan: ninja check-crates && ninja check-functional

Reviewers: Fabien, #bitcoin_abc

Reviewed By: Fabien, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D13465