dillon1000/react

[Fizz] Track Key Path (#27243)

Tracks the currently executing parent path of a task, using the name of
the component and the key or index.

This can be used to uniquely identify an instance of a component between
requests - assuming nothing in the parents has changed. Even if it has
changed, if things are properly keyed, it should still line up.

It's not used yet but we'll need this for two separate features so
should land this so we can stack on top.

Can be passed to `JSON.stringify(...)` to generate a unique key.