Introduce API to specify core data type validator for literal types

Why a major?

The API might potentially break things, therefore to be on the safer side I decided to tag a major.

4.0.0 (2025-04-27)

Features

• introduce custom data type validator (c8fc24b)
• introduce isValidDataType property (1910f2a)

Full Changelog: v3.0.0...v4.0.0