Add small vibration when the MoreKeys Panel opens

[BastianTrifork]

Add haptic feedback when opening more-keys popup

Feature: Implements #1550
Summary

This PR adds haptic feedback when the more-keys popup (shown on long-press for accents, symbols, etc.) is opened. The feedback uses the existing "Vibrate on keypress" setting, so users who have vibration enabled will now also get a short vibration when the popup appears.

Details:

• Haptic feedback is triggered in MainKeyboardView.onShowMoreKeysPanel(), using the same vibration manager as regular keypresses.
• The vibration duration is set to a short value (5ms), consistent with other feedback in the app.

Motivation

This improves the user experience for those accustomed to haptic feedback on popups (e.g., from Microsoft SwiftKey), providing a more responsive and tactile feel.

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This is my first PR to a public project, If i need to change anything, please let me know :)

Closes #1550.

[abb128]

Thank you for your contribution! Unfortunately, the code doesn't compile as-is and fails with the following errors

/home/abb128/Documents/latinime/java/src/org/futo/inputmethod/keyboard/MainKeyboardView.java:650: error: cannot find symbol
        if (settingsValues.mVibrateOn) {
            ^
  symbol:   variable settingsValues
  location: class MainKeyboardView
/home/abb128/Documents/latinime/java/src/org/futo/inputmethod/keyboard/MainKeyboardView.java:652: error: cannot find symbol
            feedbackManager.vibrate(5);
            ^
  symbol:   variable feedbackManager
  location: class MainKeyboardView

It's usually a good idea to build and test your changes before opening a PR. You can find build instructions in the README: https://github.com/futo-org/android-keyboard?tab=readme-ov-file#building