aconfig: move CodegenMode to codegen crate

This change moves CodegenMode to codegen crate.

Bug: 311152507
Test: ateset aconfig.test
Change-Id: I4f64cdbdc3d1b419412012560bfe03344b2b8faf

tools/aconfig/src/codegen/mod.rs

@@ -19,6 +19,7 @@ pub mod java;
 pub mod rust;
 
 use anyhow::{ensure, Result};
+use clap::ValueEnum;
 
 pub fn is_valid_name_ident(s: &str) -> bool {
     // Identifiers must match [a-z][a-z0-9_]*, except consecutive underscores are not allowed
@@ -52,6 +53,13 @@ pub fn create_device_config_ident(package: &str, flag_name: &str) -> Result<Stri
     Ok(format!("{}.{}", package, flag_name))
 }
 
+#[derive(Copy, Clone, Debug, PartialEq, Eq, ValueEnum)]
+pub enum CodegenMode {
+    Production,
+    Test,
+    Exported,
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;