[CDF-25260] 🦇  Dump agents (#1764)

# Description

Stacked on #1763

A common workflow is that the user creates a CDF resource using the
fusion UI in a CDF dev project. Then, they dump the resources down to
YAML configuration, which is checked into version control, and deployed
in a CI/CD to a CDF prod project.

This PR adds support for dumping agents.

## Changelog

- [x] Patch
- [ ] Minor
- [ ] Skip

## cdf

### Added

- [alpha] Support dumping agent, `cdf dump agents`. 

## templates

No changes.
