feat(gs/achilles): Codegen string literals

Codegen string literals to LLVM as (for now) global C string pointers

Change-Id: I6dcd7fa25a7806a2f708a8e9275c9a01174fd0cf
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2613
Tested-by: BuildkiteCI
Reviewed-by: glittershark <grfn@gws.fyi>

users/glittershark/achilles/src/codegen/llvm.rs

@@ -92,7 +92,11 @@ impl<'ctx, 'ast> Codegen<'ctx, 'ast> {
                     Literal::Bool(b) => Ok(AnyValueEnum::IntValue(
                         ty.const_int(if *b { 1 } else { 0 }, false),
                     )),
-                    Literal::String(_) => todo!(),
+                    Literal::String(s) => Ok(self
+                        .builder
+                        .build_global_string_ptr(s, "s")
+                        .as_pointer_value()
+                        .into()),
                 }
             }
             Expr::UnaryOp { op, rhs, .. } => {