Merge #8674

8674: fix for #8664: Emit folding ranges for multi-line where clauses r=matklad a=m5tfi

#8664 

I added a test that assert folding multi-line where clauses while leaving single lined one. Please, let me know if the code needs further improvements.

Co-authored-by: m5tfi <72708423+m5tfi@users.noreply.github.com>

crates/rust-analyzer/src/to_proto.rs

@@ -524,6 +524,7 @@ pub(crate) fn folding_range(
         | FoldKind::ArgList
         | FoldKind::Consts
         | FoldKind::Statics
+        | FoldKind::WhereClause
         | FoldKind::Array => None,
     };