Introduce extension-cli binary, for packaging extensions in CI (#9523)

This will be used in the
[extensions](https://github.com/zed-industries/extensions) repository
for packaging the extensions that users submit.

Release Notes:

- N/A

---------

Co-authored-by: Marshall Bowers <elliott.codes@gmail.com>

crates/extension_cli/Cargo.toml

@@ -0,0 +1,23 @@
+[package]
+name = "extension_cli"
+version = "0.1.0"
+edition = "2021"
+publish = false
+license = "GPL-3.0-or-later"
+
+[lints]
+workspace = true
+
+[dependencies]
+anyhow.workspace = true
+clap = { workspace = true, features = ["derive"] }
+env_logger.workspace = true
+fs.workspace = true
+extension.workspace = true
+language.workspace = true
+log.workspace = true
+theme.workspace = true
+tokio.workspace = true
+toml.workspace = true
+tree-sitter.workspace = true
+wasmtime.workspace = true