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.

Avoid suppressing Arabic numerals as morekeys when number row is active (for languages that use Indo-Arabic numerals)

This was done by looking at characters listed on the Wikipedia language recognition chart[0] for each language, finding the last character in the array that the language uses and splitting the rest off into misc. This was partially automated, but there is potential that there may be errors for some languages. All of the keys should still be there if misc keys are enabled, so the keyboard should still be usable for all affected languages even if there were errors, if misc keys are enabled.

[0] https://en.wikipedia.org/wiki/Wikipedia:Language_recognition_chart