Add --wait to promotion command

[christianh814]

Checklist

• I've searched the issue queue to verify this is not a duplicate feature request.
• I've pasted the output of kargo version, if applicable.
• I've pasted logs, if applicable.

Proposed Feature

Add a --wait option to kargo promote so the CLI won't return until the promotion succeeds or fails

Example:

kargo promote --project kargo-demo --freight-alias frisky-wookie --stage test --wait

Motivation

Some users may opt to script (or use kargo cli in a CI process) and need the promote operation to be a blocking operation.

Suggested Implementation

No suggestions but something to keep in mind is other places where a wait should be implemented. There should also be a timeout condition like in kubectl so it won't wait indefinitely (like --timeout=300s)

[hiddeco]

This has likely become more important since #1613, as Promotions can be long(er) running now.