Support for different preference input types

[nikolamajcen]

Based on #27, I've created a proposed solution without breaking backward compatibility for new input types.

Currently, there are only two types;

• text
• boolean

Which can be improved based on the changes @manuelvrhovac created in the PR mentioned. Also, additionally I added support for custom validators (two for now), which are type dependent and can be easily used on the item level.

@manuelvrhovac I would suggest checking this implementation (as this is an example of how we can simplify things), but with a new feature and idea you proposed. Let me know what you think.

Note
This is still WIP and should be discussed.

[nikolamajcen]

Due to the SwiftUI re-write for v2.0.0 I believe we can close this one, correct @ZvonimirMedak? If needed, we can use similar approach and make new components for UIKit.

[ZvonimirMedak]

Closing this one due to the SwiftUI rewrite, and the amount of changes that would be necessary for this PR. We will pick it up later on, and use the same approach but using SwiftUI