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/collab/Cargo.toml

@@ -54,7 +54,7 @@ rustc-demangle.workspace = true
 telemetry_events.workspace = true
 text.workspace = true
 time.workspace = true
-tokio = { version = "1", features = ["full"] }
+tokio.workspace = true
 toml.workspace = true
 tower = "0.4"
 tower-http = { workspace = true, features = ["trace"] }