fix: Use SVG features compatible with Qt SVG Tiny 1.1

[ratijas]

Committed on behalf of https://t.me/SergeiR

Downgrades incompatible (advanced) SVG features to something supported by a default Qt SVG rendered. Besides, xlink:href is deprecated1, and in this case introduces an unnecessary indirection. Fixes these errors causing the icon to be all black in Plasma and Qt apps:

qt.svg: icon.svg:27:6: Could not resolve property: #pattern1888
qt.svg: icon.svg:27:6: Could not resolve property: #pattern1870

Interestingly enough, logo.svg doesn't need any adjustments, it's fine.

test.qml

import QtQuick
import QtQuick.Layouts

Window {
    width: 580
    height: 320
    visible: true
    title: qsTr("btop")

    component Showcase : ColumnLayout {
        id: comp

        required property string text
        required property url url
        readonly property int size: 256

        Rectangle {
            Layout.preferredHeight: comp.size + border.width * 2
            Layout.preferredWidth: comp.size + border.width * 2
            border.width: 2
            border.color: "gray"

            Image {
                anchors.centerIn: parent
                height: comp.size
                width: comp.size
                source: comp.url
            }
        }

        Text {
            text: comp.text
            font.pixelSize: 36
            Layout.fillWidth: true
            horizontalAlignment: Text.AlignHCenter
        }
    }

    RowLayout {
        id: item

        anchors.centerIn: parent
        spacing: 16

        Showcase {
            url: "old/icon.svg"
            text: "Old"
        }


        Showcase {
            url: "new/icon.svg"
            text: "New"
        }
    }

    Component.onCompleted: {
        contentItem.grabToImage((result) => {
            result.saveToFile("comparison.png")
        })
    }
}

[vandabbin]

After a recent update on my system the icon no longer displays correctly in KDE so this fix is needed i think. I have tested with the new icon and it displays fine.