feat: restructure onhost folders and naming #849

Job	Run time
cargo clippy	2m 27s
cargo fmt	13s
codespell	11s
cargo doc	1m 37s
Unit test for embedded downloader	26s
⚖️ Check third party licenses	3m 18s
Build release binaries	2m 18s
K8s integration tests (part2)	3m 24s
K8s integration tests (part1)	3m 24s
build-widows-binary	3m 7s
Unit, docs and onhost integration tests	2m 25s
tests as root	3m 9s
K8s integration tests (flux-self-update)	3m 22s
ubuntu / stable / coverage	3m 18s
cargo shear (unused dependencies)	16s
security / Rust audit scanner	2m 36s
k8s-e2e-tests / K8s e2e tests infra	3m 24s
k8s-e2e-tests / K8s e2e tests	5s
🟢 All required checks and tests pass	2s
	39m 2s

Provide feedback