Ruby: Fix bad join in ActionControllerHelperMethod

```
[2022-01-25 12:35:14] (234s) Tuple counts for ActionController::ActionControllerHelperMethod#class#ff/2@ef816fil after 1.5s:
                      7685     ~0%     {3} r1 = JOIN ActionController::ActionControllerContextCall#ff#shared WITH Method::Method::getName_dispred#ff ON FIRST 1 OUTPUT Rhs.1, Lhs.1 'controllerClass', Lhs.0 'this'
                      13198    ~0%     {3} r2 = JOIN r1 WITH Constant::ConstantValue::getStringOrSymbol_dispred#ff_10#join_rhs ON FIRST 1 OUTPUT Lhs.1 'controllerClass', Lhs.2 'this', Rhs.1
                      15835365 ~4%     {5} r3 = JOIN r2 WITH AST::AstNode::getEnclosingModule_dispred#ff_10#join_rhs ON FIRST 1 OUTPUT Rhs.1, "helper_method", Lhs.0 'controllerClass', Lhs.1 'this', Lhs.2
                      12943    ~1%     {4} r4 = JOIN r3 WITH Call::MethodCall::getMethodName_dispred#ff ON FIRST 2 OUTPUT Lhs.4, Lhs.2 'controllerClass', Lhs.3 'this', Lhs.0
                      1146184  ~0%     {4} r5 = JOIN r4 WITH Expr::Expr::getConstantValue_dispred#ff_10#join_rhs ON FIRST 1 OUTPUT Lhs.3, Rhs.1, Lhs.1 'controllerClass', Lhs.2 'this'
                      212      ~0%     {2} r6 = JOIN r5 WITH project#Call::Call::getArgument_dispred#fff ON FIRST 2 OUTPUT Lhs.3 'this', Lhs.2 'controllerClass'
                                       return r6
```

Joining on enclosing module and name simultaneously yields a much better join.

Author: hvitved

ruby/ql/lib/codeql/ruby/frameworks/ActionController.qll

@@ -202,6 +202,21 @@ class ActionControllerRedirectResponse extends HTTP::Server::HttpRedirectRespons
   }
 }
 
+pragma[nomagic]
+private predicate isActionControllerMethod(Method m, string name, ActionControllerControllerClass c) {
+  m.getName() = name and
+  m.getEnclosingModule() = c
+}
+
+pragma[nomagic]
+private predicate actionControllerHasHelperMethodCall(ActionControllerControllerClass c, string name) {
+  exists(MethodCall mc |
+    mc.getMethodName() = "helper_method" and
+    mc.getAnArgument().getConstantValue().isStringOrSymbol(name) and
+    mc.getEnclosingModule() = c
+  )
+}
+
 /**
  * A method in an `ActionController` class that is accessible from within a
  * Rails view as a helper method. For instance, in:
@@ -222,11 +237,9 @@ class ActionControllerHelperMethod extends Method {
   private ActionControllerControllerClass controllerClass;
 
   ActionControllerHelperMethod() {
-    this.getEnclosingModule() = controllerClass and
-    exists(MethodCall helperMethodMarker |
-      helperMethodMarker.getMethodName() = "helper_method" and
-      helperMethodMarker.getAnArgument().getConstantValue().isStringOrSymbol(this.getName()) and
-      helperMethodMarker.getEnclosingModule() = controllerClass
+    exists(string name |
+      isActionControllerMethod(this, name, controllerClass) and
+      actionControllerHasHelperMethodCall(controllerClass, name)
     )
   }