we should validate VLAN range before exporting to SDX-LC

[italovalcy]

Related to what happened to end-to-end tests on atlanticwave-sdx/sdx-end-to-end-tests#110 we should validate the VLAN range before exporting to SDX-LC

[jab1982]

Please confirm we have tests for this at the end-to-end and unit tests for the components involved. See if you can find a solution remove this bug. Make sure it wasn't already fixed.