feat: proper iOS first renders measurements

[szydlovsky]

Summary

Fixes #238 on iOS.

First render on iOS was looking pretty choppy because there was no way to measure the component on the very first render, because it's still not defined at that time.
This PR adds a mock text input that gets created as soon as the Shadow Node is created, gets the initial component's props and is used for measurements before the real input is defined. After that the mock gets unmounted (when the real input is finally defined).

Before vs After

Please play the videos at x0.25 speed to notice the choppiness:

Before:

firstRenderBefore.mov

After:

firstRenderAfter.mov

Test Plan

Add a state that toggles input's visibility, with the default visibility at false. Then toggle it and see properly measured component appear with no intermediate states.

Compatibility

OS	Implemented
iOS	✅
Android	✅(already done)

[exploIF]

Just one question, I see it's currently not an issue (but maybe it's just because of the fact that example app is almost empty, and super fast), shouldn't we somehow explicitly disable emitting events for mocked input or is it redundant?

[szydlovsky]

@exploIF oh definitely. Will add it