Reintroduce missing podModulePrefix

It shouldn't be used, but it wasn't properly deprecated before, so I'm adding it back so a future me or someone else may deprecate it for good.

Author: pichfl

files/app/config/environment.ts

@@ -26,6 +26,7 @@ assert(
 
 export default config as {
   modulePrefix: string;
+  podModulePrefix?: string;
   locationType: string;
   rootURL: string;
   APP: Record<string, unknown>;