Switch to app.kubernetes.io/part-of label selector

Use `app.kubernetes.io/part-of: flux` label instead of `app.kubernetes.io/instance` to select the in-cluster objects used in flux version, check, logs and uninstall commands.

Signed-off-by: Stefan Prodan <stefan.prodan@gmail.com>

pkg/manifestgen/labels.go

@@ -0,0 +1,26 @@
+/*
+Copyright 2021 The Flux authors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package manifestgen
+
+// These labels can be used to track down the namespace, custom resource definitions, deployments,
+// services, network policies, service accounts, cluster roles and cluster role bindings belonging to Flux.
+const (
+	PartOfLabelKey   = "app.kubernetes.io/part-of"
+	PartOfLabelValue = "flux"
+	InstanceLabelKey = "app.kubernetes.io/instance"
+	VersionLabelKey  = "app.kubernetes.io/version"
+)