Bugfix: Unresponsive VTK controls on macOS resolved by initializing interactor

[LissanKoirala]

This PR adds a missing call to renderWindowInteractor.Initialize() in the graph_nav_command_line/view_map.py example.

Problem

On macOS, the VTK render window would open but did not respond to mouse/trackpad input (rotate, pan, zoom).
This happens when the interactor is started without being explicitly initialized.

Fix

Added a single line before Start():

# Start rendering.
renderWindow.Render()
renderWindowInteractor.Initialize()  # <-- Added line
renderWindowInteractor.Start()

Impact

Fixes unresponsive VTK interaction on macOS.
No change in behavior on Linux or Windows.

Tested

macOS 15.5 (24F74)
Python 3.10.18
VTK 9.5.0

Verified rotation, pan, and zoom now work with both trackpad and external mouse.