Add kwinscript subcommand for running arbitrary KWin JavaScript

[marvin1099]

Adds the kwinscript sub-command for custom kde control

Would add request #31

AI was used here, i did checking and testing myself, it is working, and looks correct in my eyes.
Would this be acceptable?

Here are some examples of what can be done with this:

Set opacity (0.0 - 1.0)

kdotool kwinscript --inline 'var w=workspace.activeWindow;if(w){w.opacity=0.5;output_result("50% opacity");}'

Get all the window stats you ever (not), wanted

Create file window_stats.js at preferred location with contents:

// Reports various properties of the currently active window.
// Uses output_result() so kdotool captures and prints the values.

var w = workspace.activeWindow;
if (!w) {
    output_error("No active window");
} else {
    output_result("--- Window Stats ---");
    output_result("ID: " + w.internalId);
    output_result("Title: " + w.caption);
    output_result("Class: " + w.resourceClass + " (" + w.resourceName + ")");
    output_result("Geometry: " + w.x + "x" + w.y + " " + w.width + "x" + w.height);
    output_result("Desktop: " + w.desktops.map(function(d) { return d.x11DesktopNumber; }).join(","));
    output_result("PID: " + w.pid);
    output_result("Minimized: " + w.minimized);
    output_result("Fullscreen: " + w.fullScreen);
    output_result("KeepAbove: " + w.keepAbove);
    output_result("KeepBelow: " + w.keepBelow);
    output_result("SkipTaskbar: " + w.skipTaskbar);
    output_result("NoBorder: " + w.noBorder);
    output_result("Opacity: " + w.opacity);
    output_result("Moveable: " + w.moveable);
    output_result("Resizeable: " + w.resizeable);
    output_result("MaximizeMode: " + w.maximizeMode);
    output_result("OnAllDesktops: " + w.onAllDesktops);
    output_result("Active: " + w.active);
    output_result("DemandsAttention: " + w.demandsAttention);
    output_result("Layer: " + w.layer);
    output_result("WindowType: " + w.windowType);
}

then run:
kdotool kwinscript --file window_stats.js

To get all the stats.