Add postinstall and associated checks, reorg checkers, root check, etc (#11)

- Explicitly fail if tool is run as nonroot.
- Add `postinstall` command
    - Add `service` readiness checker
    - Add `kube` postinstall checker
    - Add `guest type` postinstall chcker
- Add `system recorder` postinstall checker (captures everything the
preinstall one does, plus (some) Xen bits, more can be added later)
    - Reorganize, share, and split up some bits

Author: bleggett

.gitignore

@@ -33,3 +33,4 @@ cli.md
 # example outputs
 /image-cache
 edera-preinstall-report*
+edera-postinstall-report*

Cargo.toml

@@ -16,7 +16,7 @@ tar = "0.4.44"
 tokio = { version = "1", features = ["full"] }
 tokio-util = { version = "0.7" }
 tokio-stream = { version = "0.1", features = ["io-util", "net"] }
-nix = { version= "0.31", features = ["sched"] }
+nix = { version= "0.31", features = ["sched", "user"] }
 futures = "0.3"
 async-trait = "0.1"
 clap = { version = "4.5", features = ["derive"] }