Allow custom emoji

[4e554c4c]

Many platforms with emojis—such as slack, the fediverse, discord, etc. allow for custom emojis. These are usually defined by an administer and can be any PNG or webp animation, and have a custom name.

It would be nice to use this application for a similar use case, where custom emojis can be added to the keyboard and used in the flutter application.

[Fintasys]

The package is currently built to display emoji inside the Unicode standard. Allowing external emoji would require to integrate them as image files. That would require quite some refactoring of the current implementations.

It might be possible to manually add tabs with custom emoji by building a custom component.

Currently im not planning to work on this, but if anyone wants to contribute to add this feature I will review it.