refactor: Lower type-refs before type inference

This refactors how we deal with items in hir-def lowering.

- It now lowers all of them through an "ExpressionStore" (kind of a misnomer as this point) as their so called *Signatures.
- We now uniformly lower type AST into TypeRefs before type inference.
- Likewise, this moves macro expansion out of type inference, resulting in a single place where we do non-defmap macro expansion.
- Finally, this PR removes a lot of information from ItemTree, making the DefMap a lot less likely to be recomputed and have it only depend on actual early name resolution related information (not 100% true, we still have ADT fields in there but thats a follow up removal).

crates/ide/src/expand_macro.rs

@@ -550,7 +550,7 @@ macro_rules! foo {
 }
 
 fn main() {
-    let res = fo$0o!();
+    fo$0o!()
 }
 "#,
             expect![[r#"
@@ -559,6 +559,24 @@ fn main() {
         );
     }
 
+    #[test]
+    fn macro_expand_item_expansion_in_expression_call() {
+        check(
+            r#"
+macro_rules! foo {
+    () => {fn f<T>() {}};
+}
+
+fn main() {
+    let res = fo$0o!();
+}
+"#,
+            expect![[r#"
+                foo!
+                fn f<T>(){}"#]],
+        );
+    }
+
     #[test]
     fn macro_expand_derive() {
         check(