feat: Add experimental debug container command (#204)

* Basic ability to create and attach a debug container

* Add support for copying env from a target container, as well as running a custom command

* Send TTY window size

* Read asynchronously from stdin

* Default to the default namespace

* Fix stdin not being re-registered correctly with the waker

* Add debug error messages

* Let AsyncStdin reset its state once shut down

* Docs, demarcate as experimental

* Move debug container name to span

* Changelog

* ci: use install-nix-action

* fix(nix): add shebang to script (stackabletech/operator-templating#325)

* Move dependencies into root Cargo.toml

* Uglify formatting

* Change the container prefix from sble-debug- to stackablectl-debug-

* Default to the target container's image

* Run debug container as root

---------

Co-authored-by: Nick Larsen <nick.larsen@stackable.tech>

Author: nightkr

Cargo.lock

@@ -33,8 +33,10 @@ k8s-openapi = { version = "0.20", default-features = false, features = [
 kube = { version = "0.87", default-features = false, features = [
   "client",
   "rustls-tls",
+  "ws",
 ] }
 lazy_static = "1.4"
+libc = "0.2.153"
 once_cell = "1.18"
 phf = "0.11"
 phf_codegen = "0.11"
@@ -49,14 +51,16 @@ serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 serde_yaml = "0.9"
 sha2 = "0.10"
-snafu = "0.7"
+snafu = { version = "0.7", features = ["futures"] }
 stackable-operator = { git = "https://github.com/stackabletech/operator-rs.git", tag = "0.64.0" }
 tera = "1.18"
+termion = "3.0.0"
 tokio = { version = "1.29.0", features = [
   "rt-multi-thread",
   "macros",
   "fs",
   "process",
+  "io-std",
 ] }
 tower-http = "0.4"
 tracing = "0.1"

Cargo.toml

@@ -6,14 +6,15 @@ Command line tool to interact with the Stackable Data Platform
 Usage: stackablectl [OPTIONS] <COMMAND>
 
 Commands:
-  operator     Interact with single operator instead of the full platform
-  release      Interact with all operators of the platform which are released together
-  stack        Interact with stacks, which are ready-to-use product combinations
-  stacklet     Interact with deployed stacklets, which are bundles of resources and containers required to run the product
-  demo         Interact with demos, which are end-to-end usage demonstrations of the Stackable data platform
-  completions  Generate shell completions for this tool
-  cache        Interact with locally cached files
-  help         Print this message or the help of the given subcommand(s)
+  operator            Interact with single operator instead of the full platform
+  release             Interact with all operators of the platform which are released together
+  stack               Interact with stacks, which are ready-to-use product combinations
+  stacklet            Interact with deployed stacklets, which are bundles of resources and containers required to run the product
+  demo                Interact with demos, which are end-to-end usage demonstrations of the Stackable data platform
+  completions         Generate shell completions for this tool
+  cache               Interact with locally cached files
+  experimental-debug  EXPERIMENTAL: Launch a debug container for a Pod
+  help                Print this message or the help of the given subcommand(s)
 
 Options:
   -l, --log-level <LOG_LEVEL>