Add history trace command

[tonistiigi]

Includes wip trace command on top of #2891

The goal was for this command to show a trace of the build directly, for example, in Jaeger UI, but it looks like there isn't a simple API that would allow uploading a trace to an existing Jaeger image (their upload feature is an ephemeral client-side-only solution).

Options would be to upload the trace spans again via controller APIs or build our own UI-only image that we could pair with a simple server that can return the trace JSON. Separating from #2891 in order to not block that PR.

The Jaeger conversion is mostly reuse of some old code. Looks like there is also a github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/jaeger package now that probably has similar functionality.

[tonistiigi]

Added support for viewing traces using Jaeger UI.

// open trace for a ref in UI
docker buildx history trace <ref>

// open trace for last build in UI
docker buildx history trace

// save trace to file (eg. manual upload)
docker buildx history trace > trace.json

// open comparison trace with another build
docker buildx history trace --compare=otherref ref

// compare last build with the one before it
docker buildx history trace --compare '^1'

I think the UX is pretty ok and better than manual uploads and running jaeger-all-in-one. Maintainence-wise, there may be some questions though.

The old otelutil conversion code may need some updates as well. Looks like some info, like process data, could be deduplicated. I quickly looked at github.com/open-telemetry/opentelemetry-collector-contrib/pkg/translator/jaeger but I don't think we have the original format for that converter, so still some work needed to use that.