rust: Fix doc comment highlighting (#17976)

This PR fixes an issue where `/` and `!` in Rust doc comments were being
incorrectly highlighted as operators after #17734.

We solve this by removing them from the operators list and using more
scoped queries to highlight them.

Release Notes:

- N/A

---------

Co-authored-by: Max <max@zed.dev>

crates/languages/src/rust/highlights.scm

@@ -139,7 +139,6 @@
 ] @comment.doc
 
 [
-  "!"
   "!="
   "%"
   "%="
@@ -159,7 +158,6 @@
   ".."
   "..="
   "..."
-  "/"
   "/="
   ":"
   ";"
@@ -183,6 +181,10 @@
   "?"
 ] @operator
 
+; Avoid highlighting these as operators when used in doc comments.
+(unary_expression "!" @operator)
+operator: "/" @operator
+
 (lifetime) @lifetime
 
 (parameter (identifier) @variable.parameter)