Start separating authentication from connection to collab (#35471)

This pull request should be idempotent, but lays the groundwork for
avoiding to connect to collab in order to interact with AI features
provided by Zed.

Release Notes:

- N/A

---------

Co-authored-by: Marshall Bowers <git@maxdeviant.com>
Co-authored-by: Richard Feldman <oss@rtfeldman.com>

crates/language_models/Cargo.toml

@@ -44,7 +44,6 @@ ollama = { workspace = true, features = ["schemars"] }
 open_ai = { workspace = true, features = ["schemars"] }
 open_router = { workspace = true, features = ["schemars"] }
 partial-json-fixer.workspace = true
-proto.workspace = true
 release_channel.workspace = true
 schemars.workspace = true
 serde.workspace = true