Qt Quick Views: Refactor common properties/methods/signals

ListView, GridView, and TableView all inherit Flickable and provide duplicated properties/methods/signals. For example:

• All views have their own pooled()/reused() attached signals
• All views have their own forceLayout() method
• All views have their own view attached property (although the types are different)

Suggestion

Instead of inheriting Flickable directly, the views could inherit a common (uncreatable) View type which holds the common properties/methods/signals. This would make it easier to implement delegates that can be used in different View types:

// MyDelegate.qml
Item {
    function foo() { ... }
    function bar() { ... }

    View.onPooled: foo()
    View.onReusued: bar()
    Component.onCompleted: console.log("This delegate was created by a ", View.view)
}

The existing duplicated properties/methods/signals can then be deprecated.