[Android] Allow the customization of the reaction list

[K4LCIFER]

Currently the reaction list gives you the following options:
👍 , 👎 , 😄 , 🎉 , 😕 , ❤️ , 🚀 , 👀 .
I personally use a laughing emoji rather extensively, so it's annoying to have to pick it from the large emoji picker. I would much rather just replace one of the existing default emojis, like the eyes.