Drop iOS 14 Support

[kean]

The team has reached a consensus to drop iOS 14 support moving forward. Unfortunately, it's not going to be as easy as incrementing IPHONEOS_DEPLOYMENT_TARGET.

The plan is to migrate to new APIs piece by piece, test each change individually, and then when the app is ready, increment IPHONEOS_DEPLOYMENT_TARGET. I will track the changes in this ticket.

Issue: pcdRpT-2PU-p2

Main deprecations

1. UIButton.Configuration to replace previous options

There is a good post about it. The main change is probably how insets are now managed:

Insets

These are equivalent:

// Swift
if #available(iOS 15.0, *) {
    button.configuration = .plain()
    button.configuration?.contentInsets = NSDirectionalEdgeInsets(top: 0, leading: 6, bottom: 0, trailing: 6)
} else {
    button.contentEdgeInsets = UIEdgeInsets(top: 0, left: 6, bottom: 0, right: 6)
}

// Objective-C
if (@available(iOS 15, *)) {
    // - warning: Unlike Swift, you can't set button.configuration.contentInsets directly
    UIButtonConfiguration *configuration = button.configuration;
    configuration.contentInsets = NSDirectionalEdgeInsetsMake(0, 6, 0, 6);
    button.configuration = configuration;  
} else {
    button.contentEdgeInsets = UIEdgeInsetsMake(0, 6, 0 ,6);
}

You can set title and image separately (ignoring configuration), and it'll still work.

2. kUTType* and other deprecations

Example: kUTTypePNG is now UTType.png.identifier (both returns a unique type identifier, e.g. image.png)

3. UIApplication/windows deprecated