[RNMobile] Ensure keyboard opens after requesting focus on Android

[fluiddot]

What?

Ensure the keyboard always opens after the focus is requested in an Aztec view.

Why?

This issue was spotted while running the E2E tests that will be introduced in #57460. As far as we tested, seems to be only reproducible in the Android emulator. However, we decided to implement the fix to make the keyboard show logic more reliable.

How?

The function showSoftKeyboard has been updated with the following conditions:

1. If the Aztec view is already focused, then open the keyboard.
2. Otherwise, listen for focus changes, and when it gets focused open the keyboard.

ℹ️ This approach has been based on this article.

Testing Instructions

1. Build the demo app and run it on an emulator.
2. Remove all blocks.
3. Select the first and default paragraph.
4. Observe that the keyboard opens.
5. Tap on ➕ button to open the block inserter modal.
6. Dismiss the modal.
7. Observe that the paragraph is focused and the keyboard opens.
8. Add an Image block and select it.
9. Tap on ➕ button to open the block inserter modal.
10. Insert a Paragraph block.
11. Observe that the new paragraph is focused and the keyboard opens.
12. Remove the paragraph by pressing backspace.
13. Observe that the Image block gets selected and the keyboard closes.

Testing Instructions for Keyboard

N/A

Screenshots or screencast

N/A

[geriux]

LGTM! Nice work on finding the culprit and applying a solution 🚀