part of #8200

Why

This PR adds the UI for the custom range date picker.

How

• Adds a new reusable view that consists of two pickers laid out vertically.
• Selected dates are returned in a completion block.

Note: Proper date format will come in a later PR as it involves more than UI logic.

Demo

Testing

The picker is not yet integrated into the app, but you can take a look at it in its preview.
Alternatively, you can launch the view in code, for example, by replacing the list selector from the analytics hub range types.

var body: some View {
        createTimeRangeContent()
            .sheet(isPresented: $showTimeRangeSelectionView) {
                RangedDatePicker
            }
}

• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.