Rename floatingBottomCenterOriginDp to floatingBottomOriginDp to better represent actual implementation

Convert Key.java to Key.kt, update key background handling to be less convoluted, update moreKeys width and background

Layouts are now defined in yaml files at latinime/java/assets/layouts. The new system makes simple layouts significantly easier to add.

Many layouts still need to be ported over to the new system and some bugs still remain. The old layout system and XML layouts will need to be removed.