bgp: support announce policy

[zhangzujian]

• Make sure you have followed Kube-OVN Code Style.

What type of this PR

• Features

Which issue(s) this PR fixes:

Add a new BGP announce policy local.

To use this policy, annotate subnet/pod with ovn.kubernetes.io/bgp=local.

WHAT

🤖 Generated by Copilot at 0286577

This pull request adds BGP integration testing and configuration for kube-ovn. It introduces new Makefile targets and a network topology template for creating a BGP lab with containerlab. It also adds a node name flag and a BGP policy annotation for the speaker component, which announces node subnet routes to the network. It modifies the yamls/speaker.yaml file to pass the node name to the speaker container.

🤖 Generated by Copilot at 0286577

This pull request is quite a feat
It adds BGP policies to syncSubnetRoutes
It uses containerlab to test the integration
And sets the KUBE_NODE_NAME for the speaker configuration
It also adds a flag and a field for the node name to complete

HOW

🤖 Generated by Copilot at 0286577

• Define a variable CLAB_IMAGE to store the containerlab image name (link)
• Add a new target kind-init-bgp to create a network topology with a BGP router and two Kubernetes nodes using containerlab (link)
• Add a new target kind-install-bgp to enable BGP peering and route advertisement on the nodes (link)
• Add a new target kind-clean-bgp to destroy the network topology and delete the kind cluster and the kube-ovn images (link)
• Modify the clean target to also remove the yamls/clab-bgp.yaml file (link)
• Add the strings package to the import list in pkg/speaker/config.go (link)
• Add a new field NodeName to the Configuration struct in pkg/speaker/config.go (link)
• Add a new flag --node-name to the ParseFlags function in pkg/speaker/config.go (link)
• Assign the value of the --node-name flag to the NodeName field and convert it to lower case in the ParseFlags function in pkg/speaker/config.go (link)
• Modify the syncSubnetRoutes function in pkg/speaker/subnet.go to support different BGP policies specified by the ovn.kubernetes.io/bgp annotation on the subnets and pods (link)
• Add a new file yamls/clab-bgp.yaml.j2, which is a Jinja2 template for defining the network topology for the BGP test scenario using containerlab (link)
• Add a new environment variable KUBE_NODE_NAME to the kube-ovn-speaker container in the yamls/speaker.yaml file (link)