Exposing the lookup of (x,y) pixel coordinates to corresponding activeTextEditor (line,col)

<!-- ⚠️⚠️ Do Not Delete This! feature_request_template ⚠️⚠️ --> <!-- Please read our Rules of Conduct: https://opensource.microsoft.com/codeofconduct/ --> <!-- Please search existing issues to avoid creating duplicates. --> <!-- Describe the feature you'd like. --> **Problem Description** (all platforms, all versions) We are in the process of developing a plugin for our eye tracking infrastructure (iTrace) for vscode. This plugin we call iTrace-vscode will let us track a developer's eyes 👀 on specific code elements while they are working on a software task. iTrace is a client server architecture where the server sends eye tracking data to the client (in this case is vscode). The client in turn takes the raw gaze which is usually a (x,y) pixel coordinate and maps it to the line and col that pixel falls on. Please see [www.i-trace.org](www.i-trace.org) for more details. We have plugins currently for [Eclipse](https://github.com/iTrace-Dev/iTrace-Eclipse), [Visual Studio](https://github.com/iTrace-Dev/iTrace-VisualStudio), and [Atom](https://github.com/iTrace-Dev/iTrace-Atom) that are already implemented in this case. When we tried to do this for vscode. We hit a roadblock. Here is how I can best describe it: vscode provides us with a `vscode.window.activeTextEditor?.visibleRanges[0];` call, which gives us the lines of text that are currently on screen. However, we have no way to then get info from pixel measurements. vscode seems to have no API features that give information about pixel locations or measurements. If you are able to add a function call to `vscode.window.activeTextEditor` or something in the `visibleRanges` for us to give (x,y) info and get back the (line,column) data, we would be golden. Visual Studio exposes this functionality so we do have a plugin for that at [https://github.com/iTrace-Dev/iTrace-VisualStudio](https://github.com/iTrace-Dev/iTrace-VisualStudio). However, we have had numerous requests from the software engineering research and in…