adapt dualstack for vpc-nat-gw

[hongzhen-ma]

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What type of this PR

• Features

Which issue(s) this PR fixes:

Fixes #(issue-number)

WHAT

🤖 Generated by Copilot at 626fb16

This pull request adds IPv6 support and fixes some bugs for the VPC NAT gateway feature. It modifies several files in pkg/controller and pkg/ipam to handle dual-stack EIP and internal IPs and CIDRs, subnet masks, and data sources. It also updates the unit test in test/unittest/ipam/ipam.go to reflect the changes.

🤖 Generated by Copilot at 626fb16

VPC NAT gateway
Dual-stack subnets and EIPs
Autumn of changes

HOW

🤖 Generated by Copilot at 626fb16

• Modify the handleInitVpcNatGw function to support multiple service cluster IP ranges and gateway IPs for IPv4 and IPv6 (link)
• Modify the handleUpdateNatGwSubnetRoute function to use the subnetsLister instead of the ipam to get the subnet information, and to support IPv6 external and internal subnets and dual-stack subnets (link, link, link, link, link, link)
• Modify the handleAddIptablesEip, handleUpdateIptablesEip, createEipInPod, and deleteEipInPod functions to support IPv6 EIP for the VPC NAT gateway feature (link, link, link, link, link, link, link, link, link, link)
• Modify the handleAddIptablesFip, handleUpdateIptablesFip, createFipInPod, and deleteFipInPod functions to support IPv6 EIP and dual-stack internal IPs for the VPC NAT gateway feature (link, link, link, link, link, link)
• Modify the handleAddIptablesDnatRule, handleUpdateIptablesDnatRule, createDnatInPod, and deleteDnatInPod functions to support IPv6 EIP and dual-stack internal IPs for the VPC NAT gateway feature (link, link, link, link, link, link)
• Modify the handleAddIptablesSnatRule, handleUpdateIptablesSnatRule, createSnatInPod, and deleteSnatInPod functions to support IPv6 EIP and dual-stack internal CIDRs for the VPC NAT gateway feature (link, link, link, link, link, link, link, link, link)
• Modify the patchFipLabel, patchDnatLabel, and patchSnatLabel functions to use the correct label key and value for the FIP, DNAT, and SNAT objects, and to avoid conflicts with other DNAT rules that use the same EIP (link, link, link)
• Modify the patchSnatStatus function to support dual-stack internal CIDRs for the VPC NAT gateway feature (link)
• Modify the GetSubnetV4Mask function to rename it to GetSubnetMask and return both the IPv4 and IPv6 masks of the subnet (link)
• Modify the unit test for the AddOrUpdateSubnet function to use the GetSubnetMask function instead of the GetSubnetV4Mask function to get the subnet mask (link)
• Modify the log messages in the handleUpdateVpcFloatingIp, handleUpdateVpcEip, handleUpdateVpcSnat, handleUpdateVpcDnat, handleUpdateIptablesEip, handleUpdateIptablesFip, and handleUpdateIptablesDnatRule functions to use consistent and clear terms (link, link, link, link, link, link, link, link)
• Add the strings package to the imports of the pkg/controller/vpc_nat_gw_nat.go file (link)
• Remove some empty lines in the pkg/controller/vpc_nat_gw_nat.go file to improve the code formatting and readability (link, link, link, link, link, link, link, link, link)

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