Add a display_id parameter to the desktopCapturer API. (#12417)

* Add a screen_api_id parameter to the desktopCapturer API.

When using the DirectX capturer on Windows, there was previously no way
to associate desktopCapturer/getUserMedia and electron.screen API
screens. This new parameter provides the association.

* Fix non-Windows build.

* Fix Mac.

* Fix Mac harder.

* JS lint

* clang-format C++ code.

* IWYU

* display_id, Linux comment, better test

* lint

* Fix tests on Linux.

* Add display_id documentation.

lib/renderer/api/desktop-capturer.js

@@ -35,7 +35,8 @@ exports.getSources = function (options, callback) {
         results.push({
           id: source.id,
           name: source.name,
-          thumbnail: nativeImage.createFromDataURL(source.thumbnail)
+          thumbnail: nativeImage.createFromDataURL(source.thumbnail),
+          display_id: source.display_id
         })
       })
       return results