Factor out upsert and upsertAndWait

It's a common pattern in the create commands to construct a value,
then (if not exporting it) upsert it and wait for it to
reconcile. This commit factors `upsert`, which does the update/insert
bit, and `upsertAndWait`, which does the whole thing.

Since these output messages, they are methods of `apiType` (previously
`names`), so that they have access to the name of the kind they are
operating on.

Signed-off-by: Michael Bridgen <michael@weave.works>

cmd/flux/get_image_repository.go

@@ -37,8 +37,8 @@ var getImageRepositoryCmd = &cobra.Command{
   flux get image repository --all-namespaces
 `,
 	RunE: getCommand{
-		names: imageRepositoryNames,
-		list:  imageRepositoryListAdapter{&imagev1.ImageRepositoryList{}},
+		apiType: imageRepositoryType,
+		list:    imageRepositoryListAdapter{&imagev1.ImageRepositoryList{}},
 	}.run,
 }