Cluster Editing: Make pricing accurate and understandable

A few things when editing a cluster:

1. When you remove a region, or scale down a region, we need to warn the user that instances will be deleted. If there is non-replicated data on them, it will be lost.
2. When we change the blocks, we need to explain what they’ll be billed right now, and what they’ll be billed later. Highlight when those bills will hit too, based on the existing and new plans. Consider:

1. Adding a new region (gets you a new block, so partial bill)
2. Scaling up or down a region
3. Removing a region
4. Scaling up or down performance tier