Problem with deletion of postits

[mrztti]

Right now when deleting the postit, the call to destroy or to set the gameobject to inactive (both tried) results in the XR handle for spatial anchors to become invalid.

This means that once we destroy any game object, we cannot create any new ones for an unknown reason.

#3 exhibits this behviour, the problem does not come from destroying the anchor on the cloud (tested).

Problem comes from the line "SetActive(false)" in DestroyAnchor.

Testing without this line shows we can still create new postits afterwards.

The line where the crash occurs is the when we await the manager to save the anchor, which results in an openXR invalide handle error.