Properties panel does not react to selection right after modeler is created

[barmac]

Describe the Bug

Properties panel does not react to selection right after modeler is created. The selection change listener is registered during the first render which is already too late when selection is changed programmatically.

Cf. https://github.com/camunda/camunda-bpmn-js/pull/76/files#diff-229a91e301ad3a2a7db5191f99cb7fc790f8f648c1d9713a2a68e0aaecd825ebR70-R72

Steps to Reproduce

Check out this branch with a failing test.

Expected Behavior

Selection change listener is registered on module creation.

Environment

• Host (Browser/Node version), if applicable: [e.g. MS Edge 18, Chrome 69, Node 10 LTS]
• OS: [e.g. Windows 7]
• Library version: 1.x