Add support for `Group(subviews:)`, `Group(sections:)`, `ForEach(subviews:)`, and `ForEach(sections:)`

[marcelofabri]

ViewInspector currently doesn't know to handle Group(subviews:), which creates a GroupElementsOfContent view.

Here's a test that currently fails:

func testGroupSubviews() throws {
    let containerView = HStack {
        Text("First")
        Text("Second") 
        Text("Third")
    }
    
    let view = Group(subviews: containerView) { subviews in
        ForEach(Array(subviews.enumerated()), id: \.offset) { index, subview in
            subview
                .accessibilityIdentifier("subview-\(index)")
        }
    }

    let inspectedGroup = try view.inspect().group()
    XCTAssertNotNil(inspectedGroup)

    _ = try inspectedGroup.find(viewWithAccessibilityIdentifier: "subview-1")
}

I tried implementing it by looking at some of the existing examples (mainly ForEach) but I'm stuck. Here's what I've got so far:

@available(iOS 18.0, macOS 15.0, tvOS 18.0, watchOS 11.0, visionOS 2.0, *)
extension ViewType.GroupElementsOfContent: MultipleViewContent {

    public static func children(_ content: Content) throws -> LazyGroup<Content> {
        let provider = try Inspector.cast(value: content.view, type: MultipleViewProvider.self)
        let children = try provider.views()
        return LazyGroup(count: children.count) { index in
            try Inspector.unwrap(view: try children.element(at: index),
                                 medium: content.medium.resettingViewModifiers())
        }
    }
}

@available(iOS 18.0, macOS 15.0, tvOS 18.0, watchOS 11.0, visionOS 2.0, *)
extension GroupElementsOfContent: MultipleViewProvider {
    func views() throws -> LazyGroup<Any> {
        typealias Builder = (SwiftUI.SubviewsCollection) -> Content
        let builder = try Inspector
            .attribute(label: "content", value: self, type: Builder.self)
        let subviews = try Inspector
            .attribute(path: "storage|view", value: self, type: Subviews.self)
        
        // how can I use this?? `builder` requires a `SubviewsCollection` and it's initializer is not public 
    }
}

Any pointers would be very appreciated. Thanks!