dillon1000/react

using the wrong renderer's act() should warn (#15756)

* warn when using the wrong renderer's act around another renderer's updates

like it says. it uses a real object as the sigil (instead of just a boolean). specifically, it uses a renderer's flushPassiveEffects as the sigil. We also run tests for this separate from our main suite (which doesn't allow loading multiple renderers in a suite), but makes sure to run this in CI as well.

* unneeded (and wrong) comment

* run the dom fixture on CI

* update the sigil only in __DEV__

* remove the obnoxious comment

* use an explicit export for the sigil