Add the capabilities advertised by the testpmd command "show port info"
so that test cases may be marked as requiring those capabilities:
RUNTIME_RX_QUEUE_SETUP
RUNTIME_TX_QUEUE_SETUP
RXQ_SHARE
FLOW_RULE_KEEP
FLOW_SHARED_OBJECT_KEEP

These names are copy pasted from the existing DeviceCapabilitiesFlag
class. Dynamic addition of Enum members runs into problems with typing
(mypy doesn't know about the members) and documentation generation
(Sphinx doesn't know about the members).

Signed-off-by: Juraj Linkeš <juraj.linkes@pantheon.tech>