Add support for mijn.host DNS challenge

[peterv99]

Shamefully stolen from stalled pull request by shubhamku044. Pull request: #5287

[github-actions]

Welcome
First thing: don't send PR to the master branch, please send to the dev branch instead.
Please make sure you've read our DNS API Dev Guide and DNS-API-Test.
Then reply on this message, otherwise, your code will not be reviewed or merged.
Please also make sure to add/update the usage here: https://github.com/acmesh-official/acme.sh/wiki/dnsapi2
We look forward to reviewing your Pull request shortly ✨
注意: 必须通过了 DNS-API-Test 才会被 review. 无论是修改, 还是新加的 dns api, 都必须确保通过这个测试.

[peterv99]

Copied this from #5287 because it seems stalled. Added secrets so actions should run.

[peterv99]

I'm having issues with the action. The Docker run fails with "Supported validation types are: dns-01 , but you specified: http-01". Secrets have been set, any clues on how to debug this further?

[Neilpang]

clone the acmetest project on any linux machine.
run the le_test_dnsapi in the letest.sh.