This moves the HelmChart template handling to a separate reconciler,
with predicates detecing relevant changes. The idea is that this would
both facilitate working _without_ chart templates but with references
in the future, and to reduce cognitive load while working with
reconciler logic.
The predicate uses `DeepEqual` from `k8s.io/apimachinery/pkg/api/equality`
to inspect the Chart template objects of the old and new HelmRelease
object in the update event.
The reconciler uses server-side apply to create or update the HelmChart
on the cluster, and emits an event based on the change set of the
action. It does not produce any diff yet, as the server-side apply
library at present does not provide a way to gain access to an "old"
versus "new" objects after performing an apply. The `diff` package
has however been prepared to allow diffing Unstructured objects.
As this reconciler has a separate life-cycle, a new
`chart.finalizers.fluxcd.io` finalizer has been introduced to ensure
a HelmChart is properly garbage collected before the HelmRelease is
allowed to be deleted.
The implementation on the release reconciler's end is a rough sketch,
but in working shape. The foresight is that much of the reconciler will
change when the release logic will be adjusted to work with the earlier
introduced storage observer.
Signed-off-by: Hidde Beydals <hello@hidde.co>