Imports of dockerfile2llb command

PathSynopsis
contextPackage context defines the Context type, which carries deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes.
encoding/jsonPackage json implements encoding and decoding of JSON as defined in RFC 7159.
flagPackage flag implements command-line flag parsing.
github.com/moby/buildkit/client/llb
github.com/moby/buildkit/client/llb/imagemetaresolver
github.com/moby/buildkit/frontend/dockerfile/dockerfile2llb
github.com/moby/buildkit/frontend/dockerui
github.com/moby/buildkit/solver/pb
github.com/moby/buildkit/util/appcontext
github.com/sirupsen/logrusPackage logrus is a structured logger for Go, completely API compatible with the standard library logger.
ioPackage io provides basic interfaces to I/O primitives.
osPackage os provides a platform-independent interface to operating system functionality.