[dtdesign]

The concept of protecting styles was meant to provide better updates but it was too tempting for users to drop the protection. The problem is that this never solves a problem and instead creates new ones because a then customized style has a high chance of being bricked the moment an update lands.

Another short-coming is the customization of colors which means that once a value has been altered, it is not possible to recover its value. Reinstalling the style would wipe other changes too which makes it difficult to experiment without having to maintain dozens of copies.

This PR changes the situation in two ways:

1. Styles imported through packages will remain protected at all times, ensuring proper update support. Creating a copy is the only way to escape this, creating a style that is no longer attached to a package.
2. Newly imported styles as well as updated styles will now track the authored value for colors, offering a button to restore an individual value if the user wants to.