build: report docker feature detection failures

[crazy-max]

fixes #3266

Return Docker feature detection errors instead of reporting unsupported manifest lists, and cache only successful results per Docker context so failed probes can be retried. Probe the builder daemon for the docker driver and the load destination for other drivers, while skipping daemon detection for tarball exports.

The driver-level ListWorkers feature cache has a similar error-handling issue and can be addressed in a follow-up:

buildx/driver/docker/driver.go

Lines 83 to 103 in ddf35fc

	d.features.once.Do(func() {
	var useContainerdSnapshotter bool
	if c, err := d.Client(ctx); err == nil {
	workers, _ := c.ListWorkers(ctx)
	for _, w := range workers {
	if _, ok := w.Labels["org.mobyproject.buildkit.worker.snapshotter"]; ok {
	useContainerdSnapshotter = true
	}
	}
	c.Close()
	}
	d.features.list = map[driver.Feature]bool{
	driver.OCIExporter: useContainerdSnapshotter,
	driver.DockerExporter: useContainerdSnapshotter,
	driver.CacheExport: useContainerdSnapshotter,
	driver.MultiPlatform: useContainerdSnapshotter,
	driver.DirectPush: useContainerdSnapshotter,
	driver.PreferImageDigest: useContainerdSnapshotter,
	driver.DefaultLoad: true,
	}
	})

Its Features interface cannot return errors, so simply allowing failed probes to retry could change capability results midway through a build. An early failure could disable default provenance, while a later successful probe allows the build to proceed without it. Fixing that safely requires propagating detection errors through the driver interface and its callers, which is broader than this targeted fix.