Changes: - Remove the strange header-only variant of libs/image - Rename KtxBundle => Ktx1Bundle - Move image/KtxUtility => ktxreader/Ktx1Reader - Add unit test for Ktx1Reader and test stub for KTX2. Notes: - Ktx1Bundle does not depend on Filament and is used by cmgen and mipgen to generate KTX files. - Ktx1Reader has a dependency on Filament and should therefore live in a separate library, which it now does.