feat: support windows property retrieving using KWin workspace API

I'm submitting a ...

feature request

What is the current behavior?

In wayland, Qt app have no direct access to window properties. These information can only be retrived from KWin side, i.e. the compositor.

More specifically, one window's property can be retrived by accessing the KWin::Window class's property, internalId. Having this id, the window's property can be easily accessed by calling the getWindowInfo(id) function provided by the DBus interface of KWin, or accessing them inside the plugin directly.

In this plugin, a dbus API for inquiring one windows's internalId is needed as a minimum option.

For information about writing KWin plugin, see: https://github.com/KDE/kwin/tree/master/examples/plugin

For KWin Scripting API, see https://develop.kde.org/docs/plasma/kwin/api/

Other information

After doing this, corresponding function in LingmoUI should also change.