This PR adjusts how UI elements are rendered inside of full-size editors to scale with the configured `buffer_font_size`. This fixes some issues where UI elements (such as the `IconButton`s used for code action and task run indicators) would not scale as the `buffer_font_size` was changed. We achieve this by changing the rem size when rendering the `EditorElement`, with a rem size that is derived from the `buffer_font_size`. `WindowContext` now has a new `with_rem_size` method that can be used to render an element with a given rem size. Note that this can only be called during `request_layout`, `prepaint`, or `paint`, similar to `with_text_style` or `with_content_mask`. ### Before <img width="1264" alt="Screenshot 2024-05-14 at 2 15 39 PM" src="https://github.com/zed-industries/zed/assets/1486634/05ad7f8d-c62f-4baa-bffd-38cace7f3710"> <img width="1264" alt="Screenshot 2024-05-14 at 2 15 49 PM" src="https://github.com/zed-industries/zed/assets/1486634/254cd11c-3723-488f-ab3d-ed653169056c"> ### After <img width="1264" alt="Screenshot 2024-05-14 at 2 13 02 PM" src="https://github.com/zed-industries/zed/assets/1486634/c8dad309-62a4-444f-bfeb-a0009dc08c03"> <img width="1264" alt="Screenshot 2024-05-14 at 2 13 06 PM" src="https://github.com/zed-industries/zed/assets/1486634/4d9a3a52-9656-4768-b210-840b4884e381"> Note: This diff is best viewed with whitespace changes hidden: <img width="245" alt="Screenshot 2024-05-14 at 2 22 45 PM" src="https://github.com/zed-industries/zed/assets/1486634/7cb9829f-9c1b-4224-95be-82182017ed90"> Release Notes: - Changed UI elements within the editor to scale based on `buffer_font_size` (e.g., code action indicators, task run indicators, etc.).