Collapsed subprocess paste & undo bugfix

[jarekdanielak]

Problem

When a collapsed subprocess with children is pasted, the children are first created on the canvas root and then moved into the new subprocess.

When this action is undone, editor crashes because it attempts to move an element to the parent which is already removed from the canvas.

This seems to be a problem with order of operations - our subprocess implementation should first create all elements, then move them and undo those in the opposite order, but it seems to revert move action for some elements which parent was already removed (shape.create.revert).

Proposed solution

This pull request adds a test to cover this case (569ce9f) and proposes to move children into the new subprocess after all elements are created.

Unfortunately, this causes a problem with text annotations and labels which are not getting copied now.

Additional context

For more detailed debugging discussion see bpmn-io/diagram-js#957 (comment) and below.

Closes #2269

Checklist

To ensure you provided everything we need to look at your PR:

• Brief textual description of the changes present
• Visual demo attached
• Steps to try out present, i.e. using the @bpmn-io/sr tool
• Related issue linked via Closes {LINK_TO_ISSUE} or Related to {LINK_TO_ISSUE}