Fix top row of emoji reaction picker on small displays

[SpiritCroc]

Emojis were not showing if not enough space, so allow scrolling there.

Before:

After:

Signed-off-by: Tobias Büttner dev@spiritcroc.de

Pull Request Checklist

• Changes has been tested on an Android device or Android emulator with API 21
• UI change has been tested on both light and dark themes
• Pull request is based on the develop branch
• Pull request includes a new file under ./changelog.d. See https://github.com/vector-im/element-android/blob/develop/CONTRIBUTING.md#changelog
• Pull request includes screenshots or videos if containing UI changes
• Pull request includes a sign off

[bmarty]

Thanks for the fix. I propose another way to fix that, please tell me what do you think about it.