check readiness using kstatus

This change replaces all the many functions and ways of calculating
readiness of objects into one unified way that uses kstatus.Compute() to
check if the object is in progress or current. Only the objects that are
current are considered to be ready. This takes advantage of the kstatus
compatibility of Flux's APIs and also makes sure that they remain
kstatus compatible.

The new isObjectReady() function is also aware of static/statusless
objects and knows how to check their readiness using kstatus. This
prepares the CLI for the upcoming static API objects.

All the is*Ready() functions for specific objects have been removed.

This change doesn't affect any of the existing tests results.

Introduce suspend and resume subcommands for alert-provider.

Signed-off-by: Sunny <darkowlzz@protonmail.com>

cmd/flux/suspend_alertprovider.go

@@ -0,0 +1,56 @@
+/*
+Copyright 2023 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 main
+
+import (
+	"github.com/spf13/cobra"
+
+	notificationv1 "github.com/fluxcd/notification-controller/api/v1beta2"
+)
+
+var suspendAlertProviderCmd = &cobra.Command{
+	Use:   "alert-provider [name]",
+	Short: "Suspend reconciliation of Provider",
+	Long:  `The suspend command disables the reconciliation of a Provider resource.`,
+	Example: `  # Suspend reconciliation for an existing Provider
+  flux suspend alert-provider main
+
+  # Suspend reconciliation for multiple Providers
+  flux suspend alert-providers main-1 main-2`,
+	ValidArgsFunction: resourceNamesCompletionFunc(notificationv1.GroupVersion.WithKind(notificationv1.ProviderKind)),
+	RunE: suspendCommand{
+		apiType: alertProviderType,
+		object:  &alertProviderAdapter{&notificationv1.Provider{}},
+		list:    &alertProviderListAdapter{&notificationv1.ProviderList{}},
+	}.run,
+}
+
+func init() {
+	suspendCmd.AddCommand(suspendAlertProviderCmd)
+}
+
+func (obj alertProviderAdapter) isSuspended() bool {
+	return obj.Provider.Spec.Suspend
+}
+
+func (obj alertProviderAdapter) setSuspended() {
+	obj.Provider.Spec.Suspend = true
+}
+
+func (a alertProviderListAdapter) item(i int) suspendable {
+	return &alertProviderAdapter{&a.ProviderList.Items[i]}
+}