Warning system refactoring (part 1) (#16799)

* Rename lowPriorityWarning to lowPriorityWarningWithoutStack

This maintains parity with the other warning-like functions.

* Duplicate the toWarnDev tests to test toLowPriorityWarnDev

* Make a lowPriorityWarning version of warning.js

* Extract both variants in print-warning

Avoids parsing lowPriorityWarning.js itself as the way it forwards the
call to lowPriorityWarningWithoutStack is not analyzable.