Imports of spiffe-watcher command

PathSynopsis
contextPackage context defines the Context type, which carries deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes.
github.com/spiffe/go-spiffe/v2/bundle/jwtbundlePackage jwtbundle provides JWT bundle related functionality.
github.com/spiffe/go-spiffe/v2/workloadapi
google.golang.org/grpc/codesPackage codes defines the canonical error codes used by gRPC.
google.golang.org/grpc/statusPackage status implements errors returned by gRPC.
logPackage log implements a simple logging package.
osPackage os provides a platform-independent interface to operating system functionality.
os/signalPackage signal implements access to incoming signals.
syncPackage sync provides basic synchronization primitives such as mutual exclusion locks.