refactor: move `findKeyboardView` in separate file

📜 Description

Moved findKeyboardView in separate file.

💡 Motivation and Context

KeyboardMovementObserver is already pretty big file (250+ lines of the code). When we add new code then we get a lint warning telling, that files shouldn't be bigger than 250 lines of the code (excluding comments).

So in this PR I'm moving findKeyboardView function into separate file - this is a pure function with a clearly defined functionality, so it's an ideal candidate for splitting the code.

Initially I wanted to add it as extensions, but since we already have traversal folder - I decided to put it there, because in order to find a keyboardView we need to traverse through windows 🙂

📢 Changelog

iOS

added new KeyboardView file in traversal folder;
moved findKeyboardView function as static function of KeyboardView class;
removed findKeyboardView from KeyboardMovementObserver;
started to use KeyboardView.find() instead of findKeyboardView;

🤔 How Has This Been Tested?

Tested on iPhone 14 Pro (iOS 17.2, real device) + CI.

📝 Checklist

[x] CI successfully passed
[x] I added new mocks and corresponding unit-tests if library API was changed

kirillzyusko / react-native-keyboard-controller