Update binary name for extension CLI (#9541)

This PR updates the binary name used by the extension CLI from
`extension_cli` to `zed-extension`.

Release Notes:

- N/A

crates/extension_cli/Cargo.toml

@@ -8,6 +8,10 @@ license = "GPL-3.0-or-later"
 [lints]
 workspace = true
 
+[[bin]]
+name = "zed-extension"
+path = "src/main.rs"
+
 [dependencies]
 anyhow.workspace = true
 clap = { workspace = true, features = ["derive"] }