sw: move keys to separate file

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
sw: move interrupt related code to separate file

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
sw: move heater to separate file

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
sw: move uart to separate file

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
sw: switch to asynchronous operation

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>