Allow custom set of reaction emojis

### Your use case

#### What would you like to do?
The ability to change the default list of emojis when reacting to a message.

#### Why would you like to do it?
I use the laughing emoji very frequently, and every time I have to select the "plus" emoji icon and scroll to the one I want. Likewise, I almost never use the 🔥 emoji, so it is wasted space for me that could hold emoji's I frequently use.

#### How would you like to achieve it?
It could be under settings, or perhaps you could simply tap and hold one of the reaction emojis to replace the default with something else.

### Have you considered any alternatives?

_No response_

### Additional context

_No response_

### Are you willing to provide a PR?

No