refactor: Rollback: Export conversion module

Author: FrozenLemonTee

src/primitives.cppm

@@ -6,3 +6,4 @@ export import mcpplibs.primitives.underlying;
 export import mcpplibs.primitives.policy;
 export import mcpplibs.primitives.primitive;
 export import mcpplibs.primitives.operations;
+export import mcpplibs.primitives.conversion;