Rollup merge of #156353 - petrochenkov:selfdecl, r=mu001999

resolve: Set correct parent and expansion for `self` declarations

Follow up to https://github.com/rust-lang/rust/pull/146972 and https://github.com/rust-lang/rust/pull/154313.

The `parent` seems to not be used yet, it will ICE if used (https://github.com/rust-lang/rust/pull/156185 uses it).
The `expn_id` is only relevant to macros 2.0, I won't bother coming up with a test.