Add option to remove enum prefix

[sh-cho]

Motivation

In protobuf, enum names should always prefixed by ENUM_NAME_ in order to support C++ codegen.
Stripping the prefixes would be beneficial for kotlin code.

Modification

• add remove_enum_prefix option (default is false for backward compatibility)

    generateProtoTasks {
        all().forEach {
            it.plugins {
                id("kotlinx-protobuf-gen") {
                    option("remove_enum_prefix") // <-- this
                }
            }
        }
    }

Result

• Resolves [FEATURE] Prettify enum names #21