Apps: Add Example App to ./apps (#112069)

* [API Server] Add Example App for reference use.

* Remove Printlns.

* Upgrade app-sdk to v0.46.0, update apps to handle breaking changes.

* Only start the reconciler for the example app if the v1alpha1 API version is enabled.

* Some comment doc updates.

* Run make update-workspace

* Set codeowner for /apps/example

* Run make gofmt and make update-workspace

* Run prettier on apps/example/README.md

* Add COPY apps/example to Dockerfile

* Add an authorizer to the example app.

* Fix import ordering.

* Update apps/example/kinds/manifest.cue

Co-authored-by: Owen Diehl <ow.diehl@gmail.com>

* Run make update-workspace

* Re-run make gen-go for enterprise import updates

* Run make update-workspace

---------

Co-authored-by: Owen Diehl <ow.diehl@gmail.com>

apps/example/pkg/app/validation.go

@@ -0,0 +1,28 @@
+package app
+
+import (
+	"context"
+	"errors"
+
+	"github.com/grafana/grafana-app-sdk/app"
+	"github.com/grafana/grafana-app-sdk/simple"
+)
+
+var _ simple.KindValidator = NewValidator()
+
+// Validator implements simple.KindValidator
+type Validator struct{}
+
+func NewValidator() *Validator {
+	return &Validator{}
+}
+
+// Validate runs any kind of validation on incoming objects,
+// and returns an error to reject the request.
+// Here, we just reject any Example resource which is named "invalid"
+func (v *Validator) Validate(ctx context.Context, req *app.AdmissionRequest) error {
+	if req.Object.GetName() == "invalid" {
+		return errors.New("example cannot be named 'invalid'")
+	}
+	return nil
+}