This change prevents Reconciling and ArtifactOutdated conditions to be
set on HelmRepo when the checksum of a cached repo index changes.
Adds some tests to ensure that when the repo index is cached, the
revision and checksum of the returned artifact are the same as on the
existing object status.
Also adds checks for the returned artifact and chartRepo from
reconcileSource, to ensure that chartRepo is populated and the checksum
of a new potential artifact is always empty, as it's populated when the
artifact is written in the storage.
Signed-off-by: Sunny <darkowlzz@protonmail.com>