Rollup merge of #74140 - sexxi-goose:precise_hir_projections, r=nikomatsakis

Rollup merge of #74140 - sexxi-goose:precise_hir_projections, r=nikomatsakis

Make hir ProjectionKind more precise

This commit also categorizing access as Field, Index, or Subslice.

Ideas are taken from `mir::ProjectionElem`.

Proposed changes: https://github.com/rust-lang/project-rfc-2229/blob/master/hir-place-target.md

Closes: https://github.com/rust-lang/project-rfc-2229/issues/1,
Closes: https://github.com/rust-lang/project-rfc-2229/issues/2
r? @nikomatsakis @matthewjasper