Add shell-completions for dx (#5232)

* add naive shell completion using clap_complete

* first pass completions

* simpler toggle

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Co-authored-by: Jonathan Kelley <jkelleyrtp@gmail.com>

packages/cli/Cargo.toml

@@ -169,6 +169,7 @@ nucleo = "0.5.0"
 
 # 0.5.12 rust-version is too high
 home = "=0.5.11"
+clap_complete = { version = "4.5.65", features = ["unstable-dynamic"] }
 
 [target.'cfg(target_env = "musl")'.dependencies]
 git2 = { version = "0.20.2", features = ["vendored-libgit2"] }