Introduce the Screen Recorder Plugin

The screen recorder plugin allows a user to record the contents of a
screen (or part thereof), and in a second step to export the result as
various lossless or lossy animated picture or video formats. Before
exporting, the recorded video can be trimmend in length and be cropped
in size.

All functionality relies on the ffmpeg/ffprobe tools, which need to be
present on the user's system.

This initial version of the plugin introduces a settings page, and a
recording/exporting dialog with sub dialogs for recording and export
options.
Some autottests for ffmpeg/ffprobe output parsing are included.

Task-number: QTCREATORBUG-29366
Change-Id: Iaf16d369fd9088d69b1bd130185ca920d07b34c6
Reviewed-by: hjk <hjk@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>

src/plugins/plugins.qbs

@@ -76,6 +76,7 @@ Project {
         "remotelinux/remotelinux.qbs",
         "resourceeditor/resourceeditor.qbs",
         "saferenderer/saferenderer.qbs",
+        "screenrecorder/screenrecorder.qbs",
         "scxmleditor/scxmleditor.qbs",
         "serialterminal/serialterminal.qbs",
         "silversearcher/silversearcher.qbs",