macosx: Ensure directory input node is always cleared and regenerated freshly

In master we have a bug where, for directories in the Browse view, regardless of whether the child input nodes for an input node have been generated, new child nodes are generated. This leads to an ever-increasing number of duplicate input nodes being present when the same directory is opened in the browse view.

This MR fixes this bug by clearing any existing child input nodes for a given directory input node and regenerating the child input nodes, thus refreshing the child input nodes.

Signed-off-by: Claudio Cambra developer@claudiocambra.com