The vet-lite tool was useful for developing the new cmd/vet but no
longer needs to exist. This changes removes the command and moves the
main.go file to the unitchecker directory where it serves as an
example and can still be built for testing and debugging.
See also https://go-review.googlesource.com/c/go/+/150297.
Change-Id: Ic10c7cd3aeeaa2e1397dd81939616c6877f7005d
Reviewed-on: https://go-review.googlesource.com/c/150298
Reviewed-by: Michael Matloob <matloob@golang.org>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Alan Donovan