u2o support specify u2o ip on release-1.9

[changluyi]

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

What type of this PR

Examples of user facing changes:

• Features
• Bug fixes
• Docs
• Tests

Which issue(s) this PR fixes:

Fixes #(issue-number)

WHAT

🤖 Generated by Copilot at ed91ab1

This pull request adds a new feature to allow users to specify a static IP address for the underlay to overlay interconnection in each subnet. It modifies the SubnetSpec schema and struct, the subnet.go and validator.go files, and the kube-ovn-crd.yaml and crd.yaml files to support the new u2oInterconnectionIP field and its validation and reconciliation logic. It also adds a check to prevent users from enabling both the logical gateway and the underlay to overlay interconnection features at the same time.

🤖 Generated by Copilot at ed91ab1

Oh we are the coders of the kube-ovn
We make the subnets interconnect
We heave and we ho and we add a new field
u2oInterconnectionIP we set

HOW

🤖 Generated by Copilot at ed91ab1

• Add u2oInterconnectionIP field to SubnetSpec schema and struct to allow users to configure the underlay to overlay interconnection IP address for each subnet (link, link, link)
• Enqueue subnet key for processing when u2oInterconnectionIP field changes in enqueueUpdateSubnet function in subnet.go (link)
• Clear u2oInterconnectionIP field and set changed flag if u2oInterconnection field is not set in formatSubnet function in subnet.go (link)
• Acquire or release static IP address for underlay to overlay interconnection logical router port based on u2oInterconnectionIP field in reconcileU2OInterconnectionIP function in subnet.go (link)
• Validate that logicalGateway and u2oInterconnection fields are not both set to true, and that u2oInterconnectionIP field is within subnet CIDR range in ValidateSubnet function in validator.go (link)