Add screenshots to the dev containers user guide:
- Running dev containers with sub-agents (index.md, working-with-dev-containers.md)
- Discovered dev containers with Start button (index.md)
- Outdated status with rebuild option (working-with-dev-containers.md)
- Display apps disabled (customizing-dev-containers.md)
Also deletes the outdated devcontainer-agent-ports.png.
Refs #21157
This change documents the early access dev containers integration and
how to enable it, what features are available and what limitations exist
at the time of writing.
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Co-authored-by: EdwardAngert <17991901+EdwardAngert@users.noreply.github.com>