Imports of package build

PathSynopsis
github.com/docker/docker/testutil/fakecontext
gotest.tools/v3/icmdPackage icmd executes binaries and provides convenient assertions for testing the results.
ioPackage io provides basic interfaces to I/O primitives.
stringsPackage strings implements simple functions to manipulate UTF-8 encoded strings.
testingPackage testing provides support for automated testing of Go packages.