openair: Support CONFIGs in build file This modifies the openair build file to include source files based on the CONFIG values. Previously a minimal set of files to build was included with everything else excluded. Change-Id: Ic7d112cd70f9722c584929bcfffda5719012f0ee Reviewed-on: https://pigweed-review.googlesource.com/c/zephyr/zephyr-bazel/+/412037