This change uses `CapturedTheme`s to capture the themes from the context the selection handles were built in and wraps the handles with them so they can correctly inherit `Theme`s from local `Theme` widgets.

`CapturedTheme`s only captures `InheritedTheme`s, so this change also makes `_InheritedCupertinoTheme` an `InheritedTheme`. This is so we can capture themes declared under a `CupertinoTheme`, for example `primaryColor` is used as the selection handle color.

Fixes #74890