This commit rewrites the `BucketReconciler` to new standards, while
implementing the newly introduced Condition types, and trying to
adhere better to Kubernetes API conventions.
More specifically it introduces:
- Implementation of more explicit Condition types to highlight
abnormalities.
- Extensive usage of the `conditions` subpackage from `runtime`.
- Better and more conflict-resilient (status)patching of reconciled
objects using the `patch` subpackage from runtime.
- Proper implementation of kstatus' `Reconciling` and `Stalled`
conditions.
- Refactor of reconciler logic, including more efficient detection of
changes to bucket objects by making use of the etag data available,
and downloading of object files in parallel with a limited number of
workers (4).
- Integration tests that solely rely on `testenv` and do not
use Ginkgo.
There are a couple of TODOs marked in-code, these are suggestions for
the future and should be non-blocking.
In addition to the TODOs, more complex and/or edge-case test scenarios
may be added as well.
Signed-off-by: Hidde Beydals <hello@hidde.co>