This PR #47407 broke thinking models for non-zed providers (Nightly only) because we set `thinking_allowed` to `thinking_enabled` (previously `true`) [here](https://github.com/zed-industries/zed/blob/b671c8cdc5a73d49d158a84f386f8fecbfbae65a/crates/agent/src/thread.rs#L2400). The value of `thinking_enabled` eventually comes from the `LanguageModel::supports_thinking` function, which returns `false` for all models except the ones coming from Zed. This PR implements `thinking_enabled` for other providers. Before you mark this PR as ready for review, make sure that you have: - [x] Added a solid test coverage and/or screenshots from doing manual testing - [x] Done a self-review taking into account security and performance aspects - [x] Aligned any UI changes with the [UI checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist) Release Notes: - N/A