Add dynamic completion suppport

This commit adds dynamic completion support for the following commands
and flags:

- `flux delete ...` command
- `flux export ...` command
- `flux get ...` command
- `flux reconcile ...` command
- `flux resume ...` command
- `flux suspend ...` command
- `--namespace` flag
- `--context` flag

Signed-off-by: Kazuki Suda <kazuki.suda@gmail.com>

cmd/flux/reconcile_image_repository.go

@@ -30,6 +30,7 @@ var reconcileImageRepositoryCmd = &cobra.Command{
 	Long:  `The reconcile image repository command triggers a reconciliation of an ImageRepository resource and waits for it to finish.`,
 	Example: `  # Trigger an scan for an existing image repository
   flux reconcile image repository alpine`,
+	ValidArgsFunction: resourceNamesCompletionFunc(imagev1.GroupVersion.WithKind(imagev1.ImagePolicyKind)),
 	RunE: reconcileCommand{
 		apiType: imageRepositoryType,
 		object:  imageRepositoryAdapter{&imagev1.ImageRepository{}},