New: dev: add copy_int_attr_from function
Fix: dev: use interface ids from current overlay

(potential unexpected user behaviour in interfaces created on e.g. phy
graph after copied nodes wont have new interfaces added to other
overlays)
Fix: dev: catch exception if node doesn't exist (and thus can't log error as no desc)
Chg: Dev: Use the layer3 graph for IGPs for gh-206