fix(cockpit/diagram): deselect current selection
fix(cockpit/diagram): deselect current selection

Chrome behaves sometimes confusing, the mousemove event triggers even if
no mousemovement happened after a mousedown event. That's why sometimes it
is not possible to deselect your current selection on the diagram.

This commit provide a workaround to handle this strange behavior.

TitanUser/camunda-bpm-webapp,tcrossland/camunda-bpm-webapp,tcrossland/camunda-bpm-webapp,tcrossland/camunda-bpm-webapp,xlinur/camunda-bpm-webapp,TitanUser/camunda-bpm-webapp,xlinur/camunda-bpm-webapp,xlinur/camunda-bpm-webapp,nagyistoce/camunda-cockpit-ui,TitanUser/camunda-bpm-webapp,nagyistoce/camunda-cockpit-ui