Re-plan pipelines when hints change

[ryannedolan]

Summary

Closes #53.

Details

The subscription operator now sets .status.hints after planning a pipeline, and re-plans the entire pipeline whenever .status.hints diverges from .spec.hints. This means that users can modify a Subscription's hints, and the changes will take effect. For example, a users can repartition an output Kafka topic by adjusting .spec.hints.kafka.numPartitions.

Testing

I edited an existing Subscription with kubectl edit subs products and added .spec.hints.kafka.numPartitions = 16. The operator reacts accordingly:

--->%---
Planning a new pipeline for Subscription/products with SQL `SELECT "quantity", "product_id" AS KEY FROM INVENTORY."products_on_hand"`...
--->%---
Found existing topic products
--->%---
Desired partitions 16 > actual partitions 1. Creating additional partitions.
--->%---