fix: handle cluster scoped resources

[lukebond]

hit a bug in our cluster where we are trying to sync cluster scoped resources, which we've never tried before. it was getting a 404 on the creation of the resource.

at first i went and fixed the apply_mappings function, which was causing namespaces to become Some("null"). turns out that wasn't making its way into the final resource but i left it as it's a nice tidy-up anyway.

the real issue is that with namespace missing sinker assumed default namespace and creates a specifically namespaced client, that points to "default". in kube-rs this isn't the same as if you specified "default" in the yaml for a cluster-scoped resource, which would just get ignored. in kube-rs you have to use the cluster-scoped client.

i started trying to write a test for this but this code called cluster_client which requires an API, so i'd need to set up a tower mock of one and it would be a big faff.

[mkmik]

Suggested change

	let mut template = if let Some(ns) = target_namespace {
	DynamicObject::new(&target_ref.name, ar)
	.within(ns)
	.data(json!({}))
	} else {
	DynamicObject::new(&target_ref.name, ar).data(json!({}))
	};
	let mut template = DynamicObject::new(&target_ref.name, ar).data(json!({}));
	template.metadata.namespace = target_namespace;

[lukebond]

nice, thanks

[lukebond]

i did it in a few places so change it in those places too.

[mkmik]

LGTM, one minor suggestion to simplify the code

[mkmik]

similar situation here

Suggested change

	let mut source = if let Value::Null = subtree["metadata"]["namespace"] {
	DynamicObject::new(&subtree["metadata"]["name"].to_string(), &ar).data(subtree)
	} else {
	DynamicObject::new(&subtree["metadata"]["name"].to_string(), &ar)
	.within(&subtree["metadata"]["namespace"].to_string())
	.data(subtree)
	};
	let mut source = DynamicObject::new(&subtree["metadata"]["name"].to_string(), &ar).data(subtree);
	source.metadata.namespace = subtree["metadata"]["namespace"].as_str().map(str::to_string);

[mkmik]

another suggestion