Add elementTemplates.createElement API for Camunda Platform

[pinussilvestrus]

Is your feature request related to a problem? Please describe

This is a follow-up action of #582. It should be possible to do the same with the Camunda Platform element-templates feature.

const elementTemplates = modeler.get('elementTemplates');
const create = modeler.get('create');

const element = elementTemplates.createElement(template);
create.start(canvasEvent({ x: 250, y: 300 }), element);

Describe the solution you'd like

Offer the same API for the Camunda Platform element templates. That could be achieved similarly by providing a TemplateElementFactory, offering providers for each binding.

Describe alternatives you've considered

Simply build on top of the existing update template command. This comes with unexpected commands fired when using a base factory command.

Additional context

Related to #582