feat: restructure onhost folders and naming #836

Job	Run time
cargo shear (unused dependencies)	14s
Build release binaries	2m 25s
Unit test for embedded downloader	27s
codespell	13s
K8s integration tests (part1)	5m 41s
build-widows-binary	8m 56s
K8s integration tests (part2)	10m 23s
K8s integration tests (flux-self-update)	8m 29s
ubuntu / stable / coverage	4m 44s
cargo fmt	14s
Unit, docs and onhost integration tests	2m 14s
tests as root	3m 44s
⚖️ Check third party licenses	5m 1s
cargo doc	1m 43s
cargo clippy	2m 17s
k8s-e2e-tests / K8s e2e tests infra	9m 9s
security / Rust audit scanner	2m 49s
k8s-e2e-tests / K8s e2e tests	4s
🟢 All required checks and tests pass	3s
	1h 8m 50s

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