Backspace doesn't work properly in TextEdit on Android

[pouleyKetchoupp]

Godot version:
Master 92d4dee

OS/device including version:
Android 11 (Pixel 3)

Issue description:
After leaving and entering again a TextEdit control on Android, erasing the previously entered text doesn't work.

There's an error in the log when the virtual keyboard is triggered:

ERROR: TextEdit::_base_get_text: Index p_to_column = 5 is out of bounds (text[p_to_line].length() + 1 = 5).
   At: scene\gui\text_edit.cpp:4018

On this line in the new code:

String text = _base_get_text(0, 0, selection.selecting_line, selection.selecting_column);

I can confirm selection.selecting_column is 5 and not 4 in this scenario by debugging step by step on Windows (and forcing the virtual keyboard path).

This issue seems to be due to #43561 (CC @naithar)

Steps to reproduce:

1. Launch MRP (or create a scene with TextEdit and LineEdit)
2. Select the TextEdit control
3. Type abcd
4. Select the LineEdit control
   5.Select the TextEdit control again (after abcd)
5. Press backspace on the virtual keyboard
6. Observe backspace is not working

Minimal reproduction project:
android-ui-4.0.zip

[naithar]

naithar@efeb9e4 - I've ported latest commit from #43560 PR.
It should fix this issue. I'll try to test it tomorrow and make a PR for master.