Make Bendpoints Feature Configurable

[philippfromme]

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

The bendpoints feature handles multiple concerns (reconnecting start/end, adding bendpoints, moving segments) at the same time. Disabling one of these isn't straightforward (cf. https://forum.bpmn.io/t/how-to-remove-dots-on-connection-lines-that-cause-them-to-be-bent/8130/10). Users should be able to opt out of e.g. adding bendpoints through configuration instead of having to override parts of the feature.

Describe the solution you'd like

Make the bendpoints feature configurable to make customization easier.

new BpmnModeler({
  bendpoints: {
    addBendpoints: false,
    moveBendpoints: true,
    moveSegments: false
  }
});

Describe alternatives you've considered

Rely on users customizing the bendpoints feature which isn't straightforward.

Additional context

Forum topics:

• https://forum.bpmn.io/t/how-to-remove-dots-on-connection-lines-that-cause-them-to-be-bent/8130/10
• https://forum.bpmn.io/t/disable-connection-layouting-direct-lines/2415
• https://forum.bpmn.io/t/how-to-create-direct-lines-of-sequenceflow-by-default-when-connecting-elements-bpmn-diagram/6600/1