Handle errors better in the Zarf agent

[AustinAbro321]

Describe what should be investigated or refactored

Currently we return 500 errors or we warn and continue within the Zarf agent when there are errors. In most, if not all, of this situations we should instead return 400 errors (bad request) as usually the issue is that there is bad data being sent to the agent.

Things to consider:

• How does this change the user experience ? Does it make it harder to see errors, if so, maybe we should reconsider this change
• This will affect pods with containers that don't get mutated? Do we think this is significant enough to warrant a breaking change or a wait for GA?

Links to any relevant code

There are more examples but this is a few

• https://github.com/defenseunicorns/zarf/blob/main/README.md?plain=1#L1](https://github.com/defenseunicorns/zarf/blob/main/src/internal/agent/hooks/argocd-repository.go#L92)
• https://github.com/defenseunicorns/zarf/blob/main/src/internal/agent/hooks/pods.go#L79