Merge #2749

2749: Basic DocumentHighlightKind support for assignments r=matklad a=kjeremy

Wraps references per #2738 and adds limited support for DocumentHighlightKind Read/Write for simple binops assignments.

I think I need some help with determining reads/writes.

Towards #2560 

Co-authored-by: Jeremy Kolb <[email protected]>
Co-authored-by: kjeremy <[email protected]>

Author: bors[bot]

crates/ra_ide/src/lib.rs

@@ -75,7 +75,9 @@ pub use crate::{
     inlay_hints::{InlayHint, InlayKind},
     line_index::{LineCol, LineIndex},
     line_index_utils::translate_offset_with_edit,
-    references::{Reference, ReferenceKind, ReferenceSearchResult, SearchScope},
+    references::{
+        Declaration, Reference, ReferenceAccess, ReferenceKind, ReferenceSearchResult, SearchScope,
+    },
     runnables::{Runnable, RunnableKind},
     source_change::{FileSystemEdit, SourceChange, SourceFileEdit},
     syntax_highlighting::HighlightedRange,