This is a building block for implementing time-based compaction of
streams. When batches are published, a timestamp is recorded in a
secondary index pointing to the last offset of the batch. Time-based
compaction will then be able to truncate data based on the offsets
recorded in the secondary index.

This commit updates the scheduler to ensure that a Stream's generated
StatefulSet targets its corresponding headless service correctly.

The pipelines module has been refactored for more optimal storage
pattern, which has removed the need for a parallel metadata tree for the
pipeline.

The utils module has been thoroughly tested which now guards against
regressions in our data storage and indexing strategy. This also
demonstrates the expected behavior of lexicographically ordered
range scans and prefix scans.

Pipeline data indexing strategy has been updated to use a single tree and
a more efficient indexing strategy based upon lexicographical ordering
of encoded keys.

Updated to the latest rustc 1.56.0.

Refactored Pipelines to simplify the delivery pass mechanism.

Fixed a bug where active pipeline instances restored from disk were not
being properly pruned if they were already complete. As part of the
compaction story, finished pipelines will be removed from disk.

Finished pipelines are now being removed.

Tracking of stream earliest timestamp records is being tracked. This
provides the foundation for our stream compaction/truncation system.

Updated tests to assert the proper functionality of the earliest
timestamp tracking pattern.

Fixed a few small docs items in the pipeline-txp example.

Update pipeline spawning routine to ensure that only pipelines which are
part of the parent stream are spawned.

Compaction routine is now well-tested. Woot woot!

Operator has been updated to pass along retention policy config to
stream.

Updated deps across all components.

closes #99

This ensures that spurious liveness profiles do not interrupt compaction
from ever being run.

Replaced chrono w/ time crate.

Added tests for stream::subscriber::spawn_group_fetch.

Added tests for stream::subscriber::try_record_delivery_response.

Added tests for stream::subscriber::ensure_subscriber_record.