Auto merge of #14787 - HKalbasi:mir2, r=HKalbasi

MIR episode 5

This PR inits drop support (it is very broken at this stage, some things are dropped multiple time, drop scopes are wrong, ...) and adds stdout support (`println!` doesn't work since its expansion is dummy, but `stdout().write(b"hello world\n")` works if you use `RA_SYSROOT_HACK`) for interpreting. There is no useful unit test that it can interpret yet, but it is a good sign that it didn't hit a major road block yet.

In MIR lowering, it adds support for slice pattern and anonymous const blocks, and some fixes so that we can evaluate `SmolStr::new_inline` in const eval. With these changes, 57 failed mir body remains.

crates/ide/src/interpret_function.rs

@@ -42,8 +42,5 @@ fn find_and_interpret(db: &RootDatabase, position: FilePosition) -> Option<Strin
         let path = path.as_deref().unwrap_or("<unknown file>");
         format!("file://{path}#{}:{}", line_col.line + 1, line_col.col)
     };
-    match def.eval(db, span_formatter) {
-        Ok(_) => Some("pass".to_string()),
-        Err(e) => Some(e),
-    }
+    Some(def.eval(db, span_formatter))
 }