Strip prefixes from enum variants in generated code

[jacob-curley-fnal]

Per the Protobuf style guide on enums, enumerated values should be of the form

enum MyEnum {
    MY_ENUM_UNKNOWN = 0;   // Or MY_ENUM_UNSPECIFIED
    MY_ENUM_<Some value 1> = 1;
    MY_ENUM_<Some value 2> = 2;
    ...
    MY_ENUM_<Some value N> = N;
}

The Rust style guide on enums, by contrast, discourages using a repeated prefix in enums.

Would it be possible for the code generator to handle this automatically? I'd like to be able to have conformant .proto files and .rs files, without configuring the #[allow(clippy::enum_variant_names)] in the build.rs file of every project.