Merge #6251 #6310

6251: Semantic Highlight: Add Callable modifier for variables r=matklad a=GrayJack

This PR added the `HighlightModifier::Callable` variant and assigned it to variables and parameters that are fn pointers, closures and implements FnOnce trait.

This allows to colorize these variables/parameters when used in call expression.



6310: Rewrite algo::diff to support insertion and deletion r=matklad a=Veykril

This in turn also makes `algo::diff` generate finer diffs(maybe even minimal diffs?) as insertions and deletions aren't always represented as as replacements of parent nodes now.

Required for #6287 to go on.

Co-authored-by: GrayJack <gr41.j4ck@gmail.com>
Co-authored-by: Lukas Wirth <lukastw97@gmail.com>

crates/rust-analyzer/src/to_proto.rs

@@ -425,6 +425,7 @@ fn semantic_token_type_and_modifiers(
             HighlightModifier::Mutable => semantic_tokens::MUTABLE,
             HighlightModifier::Consuming => semantic_tokens::CONSUMING,
             HighlightModifier::Unsafe => semantic_tokens::UNSAFE,
+            HighlightModifier::Callable => semantic_tokens::CALLABLE,
         };
         mods |= modifier;
     }