feat: add skip tls verify configuration when fetching token from slef…

[chwetion]

add --skip-token-tls-verify flag in client to skip tls verify when fetching token.

ref issus: #3218

[tonistiigi]

What's the use case?

[chwetion]

What's the use case?

private registry such as harbor or jfrog has token fetch api, these may be access via https, when buildkitd pull image from these need verify certs, add this option to skip verify

[tonistiigi]

When this registry sends the token parameters with WWW-Authenticate is there anything in there that could be used to configure this? Doing this just for all hosts does not make much sense as buildctl has no way to predict what hosts the build request will use.

[liwenxiang]

I also encountered the same problem When Dockerfile FROM image is the self-signed image center.
add this parameter can ignore the HTTPS certificate error during the token request.

[ShoupingShan]

Is there any progress on this PR?

[tonistiigi]

#4211 #4420 should replace this