[PP-1] Deprecate the trusted data concept in configuration

Trusting data == not validating it, so there's a definite connection to all the config validation work here too 🥸

Ohhh! I've got some good news … while working on another issue ( 📌 Expose API to sort arbitrary config arrays Needs work ), I found blocking bugs (the validation logic for primitives does not match the config schema checking logic).

So I was forced to write test coverage. And I extracted that into a blocking, test-coverage-only issue. While working on that, I made the whole Config::save(has_trusted_data: TRUE) thing that this issue aims to deprecate tested separately, to make it easy to extract in the future 👍

Please review/help land 📌 PrimitiveTypeConstraintValidator vs ConfigSchemaChecker: test coverage to establish the status quo Needs review , it will help reduce the BC break risk for this issue! 😊

(Thanks @bircher for pointing me to this issue!)

As I get on new API

The only question is how to deal with upgrade tests, when we must import old config