Rework Device List model and delegates

DeviceListPage should be reworked so that it:

does not use a single _deviceDisplayInfo() function to configure its delegates, as causes binding updates to all delegates whenever any of the displayed delegate values change
uses a model of just service uids, rather than using the Global model delegates, as it does not need any of the extra data from those models

We could load delegates in this manner:

For each service type, create pages/settings/devicelist/delegates/DeviceListDelegate_<service-type>.qml.
The DeviceListPage ListView has a delegate that is a Loader, that loads the correct delegate URI based on the service type.
Have a base item DeviceListDelegate that can be extended for each delegate type.

This architecture will also make it easier to:

have custom delegates for each service type
provide third-party extensions to the Device List

In terms of the model, that can be a VeQItemModel or similar that provides the required uids.

Example:

// DeviceListPage.qml
ListView {
    delegate: Loader {
        required property string uid
        Component.onCompleted: {
            const serviceType = BackendConnection.serviceTypeFromUid(uid)
            const uri = "/pages/settings/devicelist/delegates/DeviceListDelegate_%1.qml".arg(serviceType)
            setSource(uri, { serviceUid: uid } })
        }
    }
}

// DeviceListDelegate.qml
ListItem {
    required property string serviceUid
    readonly property Device device: Device { uid: serviceUid }

    text: device.name

    ListPressArea {
        anchors.fill: parent
        onClicked: Global.pageManager.pushPage(_displayInfo.url, _displayInfo.params)
    }
}

// DeviceListDelegate_vebus.qml
DeviceListDelegate {
    id: root

    content.children: [
        Label {
            text: Global.system.systemStateToText(state.value)
        }
    ]

    VeQuickItem {
        id: state
        uid: root.serviceUid + "/State"
    }
}

victronenergy / gui-v2

Rework Device List model and delegates #1339