Remove Automatic Evaluation

- [X] Stop auto eval for Xor
- [X] Stop auto eval for ITE
- [x] Stop auto eval for Not
- [X] to_nnf
- [x] is_nnf
- [X] is_literal for predicates
- [x] Tests
- [x] Documentation
I've created an issue for this. There are still few more places where it has been used. https://github.com/sympy/sympy/issues/7593