Auto merge of #83723 - cjgillot:ownernode, r=petrochenkov
Auto merge of #83723 - cjgillot:ownernode, r=petrochenkov

Store all HIR owners in the same container

This replaces the previous storage in a BTreeMap for each of Item/ImplItem/TraitItem/ForeignItem.
This should allow for a more compact storage.

Based on https://github.com/rust-lang/rust/pull/83114

graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust