refactor: guard KeyboardLayoutGuide path through config (instead of direct checks)

[kirillzyusko]

📜 Description

Make configuration for KeyboardTrackingView.

💡 Motivation and Context

In 1.22.x I want to re-write the algorithm for tracking keyboard (yes, again) and switch back to legacy path (it looks like I found a better way of managing things and I can deliver better experience than KeyboardLayoutGuide).

But at the same time I don't want to drop the current code with KeyboardLayoutGuide. So I decided to hide it under feature flag. If users discover regressions - they can just toggle feature flag and restore old behavior.

Also in future if my method stops to work again I can also toggle feature flag and use modern path (when KeyboardLayoutGuide will be stable).

To achieve this I added KeyboardControllerConfiguration with usesKeyboardLayoutGuideTracking field. And repalced corresponding #available(iOS 26.0, *) condition to usesKeyboardLayoutGuideTracking field. Such code helps us:

• reduce code fragmentation;
• control things from one place;
• simplify the codebase and maintenance in the future.

While refactoring it I also realised that we don't need to attach invisible KeyboardLayoutGuide on older iOS versions so I also guarded this code with usesKeyboardLayoutGuideTracking flag.

📢 Changelog

iOS

• added KeyboardControllerConfiguration file;
• guard KeyboardLayoutGuide code under usesKeyboardLayoutGuideTracking flag;

🤔 How Has This Been Tested?

Tested via e2e test.

📸 Screenshots (if appropriate):

📝 Checklist

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

[github-actions]

📊 Package size report

Current size	Target Size	Difference
321567 bytes	321409 bytes	158 bytes 📈

[github-actions]

1. Guard Statement in attachToTopmostView Prevents Attachment on Older iOS
   Why: The guard statement in attachToTopmostView returns early if usesKeyboardLayoutGuideTracking is false, which skips attaching the view on older iOS versions where it's needed.
   Fix: Remove the guard statement to ensure attachment happens across all supported iOS versions.

2. Incorrect View Type Determination Based on Configuration
   Why: The view property uses the configuration to choose between self and keyboardView, risking incorrect selection if the configuration is misused or has bugs.
   Fix: Replace the condition with a direct check for iOS version 26 or higher using #available(iOS 26.0, *).

@objc var view: UIView? {
  if #available(iOS 26.0, *) {
    return self
  } else {
    return keyboardView
  }
}

This ensures the correct view is selected based on actual iOS version compatibility rather than a potentially flawed configuration setting.