Rollup merge of #143666 - nilehmann:nested_bodies_in_consumers, r=lcnr

Re-expose nested bodies in rustc_borrowck::consumers

After rust-lang/rust#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``

Author: matthiaskrgr