I need to create a JS-Library which can run workflow using new WebApi for Dynamics CRM 2016:
Again this is an action targeting contacts and running the wa_GetContactSyncStatus action, change the values to what you need them to be. Also as a side note this is against a 2016 server anything later will have a different api version for you to use. Consult the developer resources page in your crm instance to figure out what your url for the web api is.
As another side note if you have your action call another workflow that isn't synchronous it will quite probably return before your asynchronous background workflow does.