Move report_assistant_event into language_model crate (#25508)

This PR moves the `report_assistant_event` function from the
`language_models` crate to the `language_model` crate.

This allows us to drop some dependencies on `language_models`.

Release Notes:

- N/A

crates/assistant/src/inline_assistant.rs

@@ -32,11 +32,10 @@ use gpui::{
 };
 use language::{line_diff, Buffer, IndentKind, Point, Selection, TransactionId};
 use language_model::{
-    LanguageModel, LanguageModelRegistry, LanguageModelRequest, LanguageModelRequestMessage,
-    LanguageModelTextStream, Role,
+    report_assistant_event, LanguageModel, LanguageModelRegistry, LanguageModelRequest,
+    LanguageModelRequestMessage, LanguageModelTextStream, Role,
 };
 use language_model_selector::{LanguageModelSelector, LanguageModelSelectorPopoverMenu};
-use language_models::report_assistant_event;
 use multi_buffer::MultiBufferRow;
 use parking_lot::Mutex;
 use project::{CodeAction, ProjectTransaction};