[clang-tools-extra] Implemented recursive search for findImplementations (PR #177564)

[Nathan Ridge via cfe-commits]

================
@@ -306,25 +306,33 @@ std::vector<LocatedSymbol> findImplementors(llvm::DenseSet<SymbolID> IDs,
 
   RelationsRequest Req;
   Req.Predicate = Predicate;
-  Req.Subjects = std::move(IDs);
+  llvm::DenseSet<SymbolID> SeenIDs;
+  llvm::DenseSet<SymbolID> RecursiveSearch = std::move(IDs);
----------------
HighCommander4 wrote:

nit: maybe call this `Queue`?

https://github.com/llvm/llvm-project/pull/177564