Feature/subcontainers (#2720)

* wip: subcontainers

* wip: subcontainer infra

* rename NonDestroyableOverlay to SubContainerHandle

* chore: Changes to the container and other things

* wip:

* wip: fixes

* fix launch & exec

Co-authored-by: Jade <Blu-J@users.noreply.github.com>

* tweak apis

* misc fixes

* don't treat sigterm as error

* handle health check set during starting

---------

Co-authored-by: J H <dragondef@gmail.com>
Co-authored-by: Jade <Blu-J@users.noreply.github.com>

core/startos/Cargo.toml

@@ -130,7 +130,14 @@ log = "0.4.20"
 mbrman = "0.5.2"
 models = { version = "*", path = "../models" }
 new_mime_guess = "4"
-nix = { version = "0.29.0", features = ["user", "process", "signal", "fs"] }
+nix = { version = "0.29.0", features = [
+  "fs",
+  "mount",
+  "process",
+  "sched",
+  "signal",
+  "user",
+] }
 nom = "7.1.3"
 num = "0.4.1"
 num_enum = "0.7.0"
@@ -146,6 +153,7 @@ pbkdf2 = "0.12.2"
 pin-project = "1.1.3"
 pkcs8 = { version = "0.10.2", features = ["std"] }
 prettytable-rs = "0.10.0"
+procfs = "0.16.0"
 proptest = "1.3.1"
 proptest-derive = "0.5.0"
 rand = { version = "0.8.5", features = ["std"] }
@@ -166,6 +174,7 @@ serde_with = { version = "3.4.0", features = ["macros", "json"] }
 serde_yaml = { package = "serde_yml", version = "0.0.10" }
 sha2 = "0.10.2"
 shell-words = "1"
+signal-hook = "0.3.17"
 simple-logging = "2.0.2"
 socket2 = "0.5.7"
 sqlx = { version = "0.7.2", features = [
@@ -197,6 +206,9 @@ tracing-subscriber = { version = "0.3.17", features = ["env-filter"] }
 trust-dns-server = "0.23.1"
 ts-rs = { git = "https://github.com/dr-bonez/ts-rs.git", branch = "feature/top-level-as" } # "8.1.0"
 typed-builder = "0.18.0"
+which = "6.0.3"
+unix-named-pipe = "0.2.0"
+unshare = "0.7.0"
 url = { version = "2.4.1", features = ["serde"] }
 urlencoding = "2.1.3"
 uuid = { version = "1.4.1", features = ["v4"] }