Tidy up startup logging of kindWithCache source

Add a String method for the kindWithCache type to make log messages neater.

When the controller starts a source, the controller logs the message
"Starting EventSource" along with the stringification of the source.
Most source types implement the String method to provide pretty
stringifications, but the kindWithCache source type was missing this,
resulting in log messages like the following:

    2022-11-23T08:47:35.646-0600    INFO    operator.init   controller/controller.go:241    Starting EventSource    {"controller": "configurable_route_controller", "source": "&{{%!s(*v1.Role=&{{ } {      0 {{0 0 <nil>}} <nil> <nil> map[] map[] [] [] []} []}) %!s(*cache.multiNamespaceCache=&{map[openshift-config:0xc000712110 openshift-config-managed:0xc000712108 openshift-ingress:0xc0007120f8 openshift-ingress-canary:0xc000712100 openshift-ingress-operator:0xc0007120e8] 0xc000261ea0 0xc00010e190 0xc0007120e0}) %!s(chan error=<nil>) %!s(func()=<nil>)}}"}
    2022-11-23T08:47:35.646-0600    INFO    operator.init   controller/controller.go:241    Starting EventSource    {"controller": "configurable_route_controller", "source": "&{{%!s(*v1.RoleBinding=&{{ } {      0 {{0 0 <nil>}} <nil> <nil> map[] map[] [] [] []} [] {  }}) %!s(*cache.multiNamespaceCache=&{map[openshift-config:0xc000712110 openshift-config-managed:0xc000712108 openshift-ingress:0xc0007120f8 openshift-ingress-canary:0xc000712100 openshift-ingress-operator:0xc0007120e8] 0xc000261ea0 0xc00010e190 0xc0007120e0}) %!s(chan error=<nil>) %!s(func()=<nil>)}}"}
    2022-11-23T08:47:35.646-0600    INFO    operator.init   controller/controller.go:241    Starting Controller     {"controller": "configurable_route_controller"}

Because kindWithCache wraps Kind, the new String method simply calls the
wrapped Kind source's String method, which results in log messages like the
following:

    2022-11-23T08:48:43.076-0600    INFO    operator.init   controller/controller.go:241    Starting EventSource    {"controller": "configurable_route_controller", "source": "kind source: *v1.Role"}
    2022-11-23T08:48:43.078-0600    INFO    operator.init   controller/controller.go:241    Starting EventSource    {"controller": "configurable_route_controller", "source": "kind source: *v1.RoleBinding"}
    2022-11-23T08:48:43.078-0600    INFO    operator.init   controller/controller.go:241    Starting Controller     {"controller": "configurable_route_controller"}

* pkg/source/source.go: Add a String method for kindWithCache.

Author: Miciah

pkg/source/source.go

@@ -83,6 +83,10 @@ func (ks *kindWithCache) Start(ctx context.Context, handler handler.EventHandler
 	return ks.kind.Start(ctx, handler, queue, prct...)
 }
 
+func (ks *kindWithCache) String() string {
+	return ks.kind.String()
+}
+
 func (ks *kindWithCache) WaitForSync(ctx context.Context) error {
 	return ks.kind.WaitForSync(ctx)
 }