Feature: Function wrapper for the standalone ECharts provider configuration

[fireflysemantics]

It would be nice if ngx-echarts had a function wrapper like this that we could call. It's symmetric with respect to the Angular provided APIs. So we could bootstrap the application like this:

bootstrapApplication(AppComponent, {
  providers: [
    provideRouter(routes),
    provideAnimations(),
    provideHttpClient(),
    provideECharts(),
    ...
  ],
});

/**
 * Function wrapper for initializing
 * the ngx echarts provider.
 *
 * @returns The provider for ngx-echarts
 */
export function provideECharts(): Provider {
  const echartsProvider = {
    provide: NGX_ECHARTS_CONFIG,
    useFactory: () => ({ echarts: () => import('echarts') }),
  };
  return echartsProvider;
}

Also an interface for the initOpts object would be nice. Something like:

/**
 * Interface for the ECharts initOpts
 * @example
 * 
 * initOpts = {
 *     renderer: 'svg',
 *     width: 400,
 *     height: 600,
 * }; 
 */
export interface NgxEChartsInitOpts  {
    renderer?: string;
    width?: number;
    height?: number;
}