IDE+Evaluator: converge multiple type relation checks into a single sema request, NFC

From libIDE, the utility functions will invoke the request in the implementation.

tools/SourceKit/lib/SwiftLang/SwiftDocSupport.cpp

@@ -969,6 +969,7 @@ static bool reportModuleDocInfo(CompilerInvocation Invocation,
     return true;
 
   ASTContext &Ctx = CI.getASTContext();
+  registerIDERequestFunctions(Ctx.evaluator);
   (void)createTypeChecker(Ctx);
 
   SourceTextInfo IFaceInfo;