Add async flow/network failure resilience to kubernetes driver

Description

In situations where kubernetes connection is guarded or passes proxy or is using unstable connection - can we have ability to launch jobs asynchronously?

In more detail: can we have something like:

docker buildx build --detach ...

implemented where build is being initiated and once all necessary information passed over to builder connection is intentionally severed while build completes autonomously?

With above implementation and for the workflows that depend on build completion but are on unstable connection option --poll can be added:

docker buildx build --detach --poll ...

which would still launch autonomous build, but having all the build information at hand could periodically poll build status and report back all the way until completion. Which on surface will look like present synchronous flow but would be more resilient to network failures.

Start by reviewing the Kubernetes driver and the existing docker buildx build synchronous flow. Define how --detach transfers all build information before disconnecting, and how --poll tracks the autonomous build through completion. Done means unstable or severed connections no longer prevent the build from completing or reporting its status.