Draft: libtaskmanager: Delay emitting dataChanged signal

This adds a pending queue to delay emitting dataChanged() and combine dataChanged() signals with the same data role. The update frequency is limited to 10Hz.

CCBUG: 414121

Test QML code

import QtQuick 2.15
import QtQml 2.15
import QtQuick.Window 2.15

Window {
    id: root
    width: 640
    height: 480
    visible: true
    title: qsTr("Hello World")

    Timer {
        interval: 10
        running: true
        repeat: true
        onTriggered: root.title = Math.random()
    }
}

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