Redesign AnnotationInput field

Personally, I think it's too close to a chat-icon and specifically reminds me of Telegram. Not sure if there is an icon that is still meaningful and clear but less associated with a messenger.

I have serious concerns about this because I don't think it would be good if the users were driven too much in a certain way of writing and, in this case, into a "messenger logic". This can have a big impact on the way annotations are made.

I find that already the additional icons for voice input etc. are difficult in that respect, but the send button affects it the most.