language_model: Remove dependency on inline_completion_button (#20930)

This PR removes a dependency on the `inline_completion_button` crate
from the `language_model` crate.

We were taking on this dependency solely to call `initiate_sign_in`,
which can easily be moved to the `copilot` crate.

This allows `language_model` to move up in the crate dependency graph.

Release Notes:

- N/A

crates/language_model/Cargo.toml

@@ -32,7 +32,6 @@ futures.workspace = true
 google_ai = { workspace = true, features = ["schemars"] }
 gpui.workspace = true
 http_client.workspace = true
-inline_completion_button.workspace = true
 log.workspace = true
 menu.workspace = true
 ollama = { workspace = true, features = ["schemars"] }

crates/language_model/src/provider/copilot_chat.rs

@@ -383,9 +383,7 @@ impl Render for ConfigurationView {
                                         .icon_size(IconSize::Medium)
                                         .style(ui::ButtonStyle::Filled)
                                         .full_width()
-                                        .on_click(|_, cx| {
-                                            inline_completion_button::initiate_sign_in(cx)
-                                        }),
+                                        .on_click(|_, cx| copilot::initiate_sign_in(cx)),
                                 )
                                 .child(
                                     div().flex().w_full().items_center().child(