Add preserveSpace to OrganizationChart for PrimeReact

[kov7si]

Current behavior
Org Chart child nodes become hidden on collapse but occupy the same space making the org chart unnecessarily huge when all/some nodes are collapsed.

Expected behavior
The child nodes support display:none instead of visibility:hidden

Additional Information
This behaviour was already mentioned and solved in PrimeNG, it would be nice to have the same functionality in PrimeReact
Link to discussion for PrimeNg
Link to commit with fix