Allow hack/test-go.sh to support flags

Pass arguments after the package directly to go test

    hack/test-go.sh pkg/util -v -test.run=TestNewStringSet

And also allow global flags

    hack/test-go.sh "" -v
Unless I misunderstand, your ${@:2} should be wrapped in quotes.  Otherwise the shell will not preserve enbedded whitespace, but instead split on it.

e.g.

$ function foo { for a in ${@:2}; do echo __${a}__; done; }
$ foo "1 1" "2 2" "3 3"
__2__
__2__
__3__
__3__


vs

$ function foo { for a in "${@:2}"; do echo TIM: __${a}__; done; }
$ foo "1 1" "2 2" "3 3"
TIM: __2 2__
TIM: __3 3__