Imports of cue-ast-print command

PathSynopsis
cuelang.org/go/cue/parserPackage parser implements a parser for CUE source files.
cuelang.org/go/internal/astinternal
flagPackage flag implements command-line flag parsing.
fmtPackage fmt implements formatted I/O with functions analogous to C's printf and scanf.
ioPackage io provides basic interfaces to I/O primitives.
logPackage log implements a simple logging package.
osPackage os provides a platform-independent interface to operating system functionality.