Re-expose nested bodies in rustc_borrowck::consumers After https://github.com/rust-lang/rust/pull/138499, it's not possible anymore to get borrowck information for nested bodies via `get_body_with_borrowck_facts`. This PR re-exposes nested bodies by returning a map containing the typeck root and all its nested bodies. To collect the bodies, a map is added to `BorrowCheckRootCtxt`, and a body is inserted every time `do_mir_borrowck` is called. r? ``@lcnr``