Fix bug on codegen in ::prost::Enumeration

[megsdevs]

Fixes #927 and #812, caused by #853.

Reverting the changes until a working implementation + test(s) have been built.

I encourage @Leulz to address this before bringing it back in.

[megsdevs]

draft until resolved compatibility with current version of tonic

[megsdevs]

This uncovered another bug with codegen where all message data structures are not implementing the Message trait with the expected path. An example:

error[E0277]: the trait bound `grpc_codegen::Empty: prost::message::Message` is not satisfied
    --> /Users/megan/git/trade-api/target/debug/build/valorem-trade-9bf8c220466cd8d7/out/valorem.trade.v1.rs:1706:65
     |
1706 |                         let mut grpc = tonic::server::Grpc::new(codec)
     |                                        ------------------------ ^^^^^ the trait `prost::message::Message` is not implemented for `grpc_codegen::Empty`
     |                                        |
     |                                        required by a bound introduced by this call
     |
     = help: the following other types implement trait `prost::message::Message`:
               bool
               i32
               i64
               u32
               u64
               f32
               f64
               prost_types::compiler::Version
             and 76 others
     = note: required for `ProstCodec<FeeStructure, grpc_codegen::Empty>` to implement `Codec`

Open to suggestions on resolving this