Adds Hyper-V Security Groups implementation

Implements the security groups API in the Hyper-V agent.

To enable security groups on the Hyper-V agent, its config file
must contain the following option:

[SECURITYGROUP]
firewall_driver=neutron.plugins.hyperv.agent.security_groups_driver.HyperVSecurityGroupsDriver

Change-Id: I7556001557cd013c10b7f883dbf371afa8d09626
Implements: blueprint hyperv-security-groups
Minor refactoring for Hyper-V utils and tests

A separate commit in the blueprint addressed by this patch
introduces the "_filter_acls" and "_create_acl" methods
which can be used in "enable_port_metrics_collection"
as well to reduce code duplication.

This commit eliminates also some code duplication
in test_hyperv_utilsv2.py.

Implements: blueprint hyperv-security-groups

Change-Id: I48fb5389b6049641ca2649990e81e94e4c45ef7f
Merge "Adds Hyper-V Security Groups implementation"
Merge "Minor refactoring for Hyper-V utils and tests"