Add support for changing the Codestral endpoint (#41116)

```json
  "edit_predictions": {
    "codestral": {
      "api_url": "https://codestral.mistral.ai",
      "model": "codestral-latest",
      "max_tokens": 150
    }
  },
```

Release Notes:

- Added support for changing the Codestral endpoint. This was discussed
at #34371.

---------

Co-authored-by: Bennet Bo Fenner <bennetbo@gmx.de>

crates/language/src/language_settings.rs

@@ -420,6 +420,8 @@ pub struct CodestralSettings {
     pub model: Option<String>,
     /// Maximum tokens to generate.
     pub max_tokens: Option<u32>,
+    /// Custom API URL to use for Codestral.
+    pub api_url: Option<String>,
 }
 
 impl AllLanguageSettings {
@@ -636,6 +638,7 @@ impl settings::Settings for AllLanguageSettings {
         let codestral_settings = CodestralSettings {
             model: codestral.model,
             max_tokens: codestral.max_tokens,
+            api_url: codestral.api_url,
         };
 
         let enabled_in_text_threads = edit_predictions.enabled_in_text_threads.unwrap();