[REQ] Remove forked buildkit code

[pmengelbert]

What kind of request is this?

Other

What is your request or suggestion?

In #492 we are forking dockerui.Build(...) from moby/buildkit. The changes have been submitted upstream, but not yet merged or included in a release. moby/buildkit#5614 is the PR with the changes in question. It is intended to be included in v0.19.0. Once it is merged and included in a release, we should bump the buildkit version and unfork dockerui.Build(...).

Are you willing to submit PRs to contribute to this feature request?

• Yes, I am willing to implement it.