feat: add new command to migrate onhost folders #1254

Job	Run time
Build release binaries	5m 37s
tests as root	4m 1s
K8s integration tests (part2)	9m 51s
K8s integration tests (part1)	11m 38s
codespell	14s
K8s integration tests (flux-self-update)	10m 14s
ubuntu / stable / coverage	3m 16s
cargo shear (unused dependencies)	13s
⚖️ Check third party licenses	4m 46s
cargo clippy	1m 59s
Unit, docs and onhost integration tests	3m 52s
Unit test for embedded downloader	5m 20s
build-windows-binary	3m 51s
cargo doc	1m 37s
cargo fmt	16s
k8s-e2e-tests / K8s e2e tests infra	11m 12s
security / Rust audit scanner	2m 41s
k8s-e2e-tests / K8s e2e tests	5s
🟢 All required checks and tests pass	2s
	1h 20m 45s

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