Ability to remove Message Definitions

[StephenOTT]

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

When creating messages on Receive Tasks and Message Events, you can use the + button to create a new message. But once created, there is no way to delete the message.

You have to edit the XML directly and find the Message Element in question and delete it.

Describe the solution you'd like

The User should have the ability to delete the message without having to exit the XML. Leaving unused Message Element XML is bad hygiene

Describe alternatives you've considered

/

Additional context

Related to camunda/camunda-modeler#136

[pinussilvestrus]

This relates to camunda/camunda-modeler#136. It's not a bug, but a missing feature.