Remove get_nogo from context (bazel-contrib#4029)

**What type of PR is this?**
Cleanup

**What does this PR do? Why is it needed?**
It seems odd to hang helpers off the `go` context because they still
need to take `go` as a param. It's clearer to just import them.

**Which issues(s) does this PR fix?**

Fixes #

**Other notes for review**

go/private/actions/archive.bzl

@@ -12,6 +12,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+load(
+    "//go/private:context.bzl",
+    "get_nogo",
+)
 load(
     "//go/private:context.bzl",
     "get_nogo",