Allow chat messages to be edited by external plugins

[thecreativeuniverse]

This allows for more flexibility with separate chat plugins which may edit a chat message to add extra features.

[Aust1n46]

This will break the message remover because the message hash isn't being recalculated after changing the inputs.

I know the message remover is known not working on 1.19, but it does still work on older versions.