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/language_models/Cargo.toml

@@ -40,7 +40,6 @@ serde_json.workspace = true
 settings.workspace = true
 smol.workspace = true
 strum.workspace = true
-telemetry_events.workspace = true
 theme.workspace = true
 thiserror.workspace = true
 tiktoken-rs.workspace = true