xml: T9179: reject VRF names in interface-name constraint

Tab completion for source-interface and other interface leafNodes already
excludes VRF names, but the shared interface-name constraint accepted them
anyway: an existing VRF is a real net device, so it passed the file-path
existence check even though it failed the interface-name regex.

Replace the file-path validator with a new interface-exists validator that
requires the value to both exist under /sys/class/net and not be a VRF.
The regex-match fallback is unchanged, so dynamic interfaces (e.g. pppoe)
referenced before they exist still validate correctly.

0 files changed, 0 insertions, 0 deletions