Separate validation into own package

Hi, I am rising this issue in order to considerate removing the validation feature from the core, for the following reasons.

Not every project requires validation and most importantly not every project can or should support Promises. Keeping the current validation implementation as an optional package would additionally decrease the core size and help on the separation of concerns.

Thank you for considering, and for maintaining this project.

Start by reviewing the current validation implementation in the core package and how the repository structures optional packages. Determine the package boundary and dependency changes needed to remove validation and Promise support from core; done means validation remains available separately without requiring those features in core.

Written by the indexing model from the issue text.