Remove dependents of language_models (#25511)

This PR removes the dependents of the `language_models` crate.

The following types have been moved from `language_models` to
`language_model` to facilitate this:

- `LlmApiToken`
- `RefreshLlmTokenListener`
- `MaxMonthlySpendReachedError`
- `PaymentRequiredError`

With this change only `zed` now depends on `language_models`.

Release Notes:

- N/A

crates/language_models/Cargo.toml

@@ -41,7 +41,6 @@ settings.workspace = true
 smol.workspace = true
 strum.workspace = true
 theme.workspace = true
-thiserror.workspace = true
 tiktoken-rs.workspace = true
 ui.workspace = true
 util.workspace = true