feat: support ipip tunnel as lan/wan interface

[pcmid]

Background

Checklist

• The Pull Request has been fully tested
• There's an entry in the CHANGELOGS
• There is a user-facing docs PR against https://github.com/daeuniverse/dae

Full Changelogs

• [Implement ...]

Issue Reference

Closes #614

Test Result

[mzz2017]

你有测试环境吗，请确认是否正常工作？

[pcmid]

@mzz2017 在我的环境中测试是没有问题的

[jschwinger233]

Thanks!

In future maybe we can get linkHdrLen based on the the L2 addr, e.g. if ip --br link shows zero mac addr with NOARP, then it's an L2-less device. (We just need to translate ip --br link command into API callings.)

[pcmid]

Thanks!

In future maybe we can get linkHdrLen based on the the L2 addr, e.g. if ip --br link shows zero mac addr with NOARP, then it's an L2-less device. (We just need to translate ip --br link command into API callings.)

We can check the size of LinkAttrs.HardwareAddr, a size of 0 might indicate that it's an L2-less device.

[pcmid]

Are there any other issues that need to be resolved with this PR?

[dae-prow]

🧪 Since the PR has been fully tested, please consider merging it.