Add CefFrame::ExecuteJavaScript variant with result callback

[magreenblatt]

Is your feature request related to a problem? Please describe.
The existing CefFrame::ExecuteJavaScript method does not currently support a result callback. The related Chromium implementation (RenderFrameHost::ExecuteJavaScript) does support a result callback.

Describe the solution you'd like
Add a variant of CefFrame::ExecuteJavaScript with a result callback.

Describe alternatives you've considered
Result callback functionality can currently be implemented using CefV8Context::Eval and CefMessageRouter. However, that is substantially more complicated for clients.

Additional context
It might also be nice to expose ExecuteJavaScriptMethod as an alternative to ExecuteJavaScript. From the Chromium docs:

  // This API allows to execute JavaScript methods in this frame, without
  // having to serialize the arguments into a single string, and is a lot
  // cheaper than ExecuteJavaScript below since it avoids the need to compile
  // and evaluate new scripts all the time.
  //
  // Calling
  //
  //   ExecuteJavaScriptMethod("obj", "foo", [1, true], callback)
  //
  // is semantically equivalent to
  //
  //   ExecuteJavaScript("obj.foo(1, true)", callback)

This would also benefit from a more concise way to construct CefListValue objects (e.g. [1, true] in the above example).