private static void writeContentsToFile(File outDir, String outFile, InputStream inputStream) throws IOException {
        String contents = IOUtils.readAll(new InputStreamReader(inputStream));
        File out = new File(outDir, outFile);
        IOUtils.writeFile(out, contents, false);
    }
Looks for schema files in config-model.jar and saves them in a temp dir. Uses schema files
in $VESPA_HOME/share/vespa/schema/[major-version].x/ otherwise

@return the directory the schema files are stored in
@throws IOException if it is not possible to read schema files
config-application-package/src/main/java/com/yahoo/config/model/application/provider/SchemaValidators.java