[chat_history] poor experience for keyboard in landscape layout

[kevmo314]

https://www.youtube.com/watch?v=us4grO1alQA

To fix this, we should probably create a dedicated UI for landscape keyboards. Something like this: https://stackoverflow.com/questions/58308754/flutter-how-to-open-full-screen-keyboard-in-landscape-mode/67334523#67334523

This will probably have to handle slash commands differently from the main UI, but we should create a custom text input overlay UI.

[SputNikPlop]

This is partially fixed by #1322 we will need a new UI for handling slash commands in landscape mode