Initialize wx component js processor

@inner
@param {Object=} opts the options to init
@param {string=} opts.processor the builtin processor name, by default `babel`
@param {Array=} opts.plugins the processor plugins
@param {string} defaultBabelProcessorName default babel processor name
function initJsProcessor(opts, defaultBabelProcessorName) {
    let plugins = (opts && opts.plugins) || [jsPlugin];
    registerProcessor({
        name: (opts && opts.processor) || defaultBabelProcessorName, // override existed processor
        hook: {
            before(file, options) {
                if (file.isWxCompScript) {
                    options.plugins || (options.plugins = []);
                    options.plugins.push.apply(options.plugins, plugins);
                }
            }
        }
    });
}