Creating a UIImageView outside a view hierarchy now crashes on iOS 18. We can
avoid this offscreen rendering technique by removing UIImage.asTintedImage(),
configuring the tint colour and template rendering on the UIImage directly, and
rendering with UIGraphicsImageRenderer instead of lower-level Core Graphics
APIs.
This included:
- Removing unavailable inits wholesale if no longer `required`
- Marking a few classes `final` so they could continue using
`Self(...)` rather than `OWSWhatever(...)`
