cni: reduce memory usage

[zhangzujian]

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

What type of this PR

• Performance

Which issue(s) this PR fixes:

This patch reduces ~9MB memory usage on each CNI call.

WHAT

🤖 Generated by Copilot at 0cae295

Refactor the cni package to be a standalone binary for linux and windows platforms. Add support for building and packaging the kube-ovn CNI plugin for amd64 and arm64 architectures.

🤖 Generated by Copilot at 0cae295

Oh we're the crew of the kube-ovn ship
And we're sailing on the Kubernetes sea
We're refactoring the cni package
To make it a standalone binary

HOW

🤖 Generated by Copilot at 0cae295

• Refactor the cni package to be a standalone binary instead of a subcommand of the kube-ovn binary (link, link, link, link, link, link, link, link)
• Remove the import of the cni package and the constant CmdCNI from the cmdmain.go file (link, link)
• Remove the case for the CmdCNI from the switch statement in the main function of the cmdmain.go file (link)
• Change the package name of the cni.go, netconf.go, and netconf_windows.go files from cni to main (link, link, link)
• Change the function name of the cni.go file from CmdMain to main (link)
• Delete the file cmd/windows/cni/main_windows.go (link)
• Add support for linux amd64 and arm64 platforms for the CNI plugin binary (link, link)
  • Add a new command to the Makefile to build the kube-ovn binary for linux amd64 platform and copy it to the dist/images directory (link)
  • Modify the command to build the kube-ovn binary for linux arm64 platform and copy it to the dist/images directory along with the other binaries (link)