Add external connectivity entities that are missing from docs

Commit adds classes:
- ProgramExternalConnectivityEntity
- RevokeExternalConnectivityEntity
in package docker_plugin_api.NetworkDriverEntities

These two are missing from integration docs:
https://github.com/moby/libnetwork/blob/master/docs/remote.md
but are present in implementation:
https://github.com/moby/libnetwork/blob/master/driverapi/driverapi.go

 docker_plugin_api/NetworkDriverEntities.py

@@ -96,3 +96,19 @@

        self.DiscoveryType = DiscoveryType
        self.DiscoveryData = DiscoveryData


class ProgramExternalConnectivityEntity:
    def __init__(self, NetworkID: str, EndpointID: str, Options: dict = None):
        if Options is None:
            Options = {}

        self.NetworkID = NetworkID
        self.EndpointID = EndpointID
        self.Options = Options


class RevokeExternalConnectivityEntity:
    def __init__(self, NetworkID: str, EndpointID: str):
        self.NetworkID = NetworkID
        self.EndpointID = EndpointID