refactor: rename FocusedInputLayoutObserver -> FocusedInputObserver

[kirillzyusko]

📜 Description

Renamed FocusedInputLayoutObserver to FocusedInputObserver.

💡 Motivation and Context

I'm planning to extend library functionality. Soon apart of observing layout of focused input I'll also do other things (such as observing the text that user is typing).

Creating another class is kind of very expensive thing, because the functionality of these two classes will be toughly bound to each other (for example when observing text-value we'll need to sync-up layout - and it's a part of current FocusedInputLayoutObserver).

So taking it into consideration I decided to rename FocusedInputLayoutObserver class to make it more generic.

📢 Changelog

iOS

• renamed FocusedInputLayoutObserver.swift file to FocusedInputObserver.swift;
• renamed all references of FocusedInputLayoutObserver to FocusedInputObserver.

Android

• renamed FocusedInputLayoutObserver.kt file to FocusedInputObserver.kt;
• renamed all references of FocusedInputLayoutObserver to FocusedInputObserver.

🤔 How Has This Been Tested?

Tested manually on Pixel 3a (API 33, emulator).

📝 Checklist

• CI successfully passed

[github-actions]

📊 Package size report

Current size	Target Size	Difference
80173 bytes	80166 bytes	7 bytes 📈