tests: add type annotations to the vpp object abstract class
tests: add type annotations to the vpp object abstract class

make it easier to detect logical mistakes.

Type: test

Change-Id: I853748ffaeebc545c8d31299f0d105405ad80bba
Signed-off-by: Paul Vinciguerra <b92f79aabe4c9c18085c7347110a52af0898a0ef@vinciconsulting.com>

FDio/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,FDio/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp