Extract the debug/namespace flags into run.Config [#67]

This is a general-purpose cleanup commit; every step except InitKube had
the same six "add the --debug and --namespace flags if applicable" code.

internal/run/config.go

@@ -20,3 +20,14 @@ func newConfig(cfg env.Config) *config {
 		stderr:    cfg.Stderr,
 	}
 }
+
+func (cfg *config) globalFlags() []string {
+	flags := []string{}
+	if cfg.debug {
+		flags = append(flags, "--debug")
+	}
+	if cfg.namespace != "" {
+		flags = append(flags, "--namespace", cfg.namespace)
+	}
+	return flags
+}