Restore plugin system

[barmac]

Is your feature request related to a problem? Please describe.

There is currently no plugins system on next branch Modeler.

Describe the solution you'd like

We need to restore plugin system as it was in old Camunda Modeler. To achieve this, we need to:

• Restore menu endpoint
• Restore style endpoint
• Restore script endpoint

Additional context

Previously, we provided endpoints to add custom style, menu and script. The script could register additional bpmn-js and bpmn-moddle modules thanks to https://github.com/camunda/camunda-modeler-plugin-helpers

[barmac]

Related repositories:
https://github.com/camunda/camunda-modeler-plugin-example
https://github.com/camunda/camunda-modeler-plugin-helpers

[pSub]

Support for dmn plugins would be really nice! Do you have plans for it?

[nikku]

Not on our immediate roadmap (but definitely nice to have some day, maybe).

How would you like to extend dmn-js?

[pSub]

I am developing an analysis tool for dmn (https://github.com/red6/dmn-check). That tool started out as a Maven plugin, but I would like to integrate it into the modeler (ie. highlighting errors in the decision table / diagram).