cli: Treat first argument as name of release channel to use for the cli (#10856)

With this commit, it is now possible to invoke cli with a release
channel of bundle as an argument. E.g: `zed stable some_arguments` will
find CLI binary of Stable channel installed on your machine and invoke
it with `some_arguments` (so the first argument is essentially omitted).

Fixes #10851

Release Notes:

- CLI now accepts an optional name of release channel as it's first
argument. For example, `zed stable` will always use your Stable
installation's CLI. Trailing args are passed along.

crates/cli/Cargo.toml

@@ -20,6 +20,7 @@ path = "src/main.rs"
 anyhow.workspace = true
 clap.workspace = true
 ipc-channel = "0.18"
+release_channel.workspace = true
 serde.workspace = true
 util.workspace = true