Have inspectors explicitly declare dependencies on other inspectors

### What needs to get done

- Modify inspectors implementation and likely the `Inspector` interface to enable inspectors listing other inspectors they depend on.
- Rework `inspectors.New()` to dynamically order the inspectors based on their dependencies.
- Cleanup the error handling in inspectors dealing with potentially missing metadata from previous inspectors

### Why it needs to get done

Inspectors are run in the order they are declared in `insList` in `inspectors.New()`. Reordering this slice, or adding new inspector at the wrong position could have unintended and hard to diagnose behavior.
Moreover existing dependency between inspectors is implicit and could change on a minor code change.

Start with the inspectors implementation, the Inspector interface, and inspectors.New(), including its insList ordering. Define how inspectors declare dependencies, make New() order them dynamically, and clean up missing-metadata error handling; done means dependency order no longer relies on slice position and existing inspector behavior remains correct.

Written by the indexing model from the issue text.