Support for @Entry macro

The @Entry macro is a nice shorthand for needing to make a custom EnvironmentKey. It would be nice is Skip supported it. E.g.:

struct SomeView: View {
    @Environment(\. myCustomValue) var myCustomValue: String
    var body: some View { … }
}

could be implemented with:

extension EnvironmentValues {
    @Entry var myCustomValue: String = "Default value"
    @Entry var anotherCustomValue = true
}

instead of:

private struct MyCustomValueKey: EnvironmentKey {
    static let defaultValue = "Default value"
}

extension EnvironmentValues {
    public var myCustomValue: String {
        get { self[MyCustomValueKey.self] }
        set { self[MyCustomValueKey.self] = newValue }
    }
}

Start with Apple's @Entry documentation and the existing EnvironmentValues and EnvironmentKey support in Skip. Trace how SwiftUI environment declarations are translated for Android, then verify that the examples support default values and multiple custom entries without requiring manually defined keys.