Add LM Studio support to the Assistant (#23097)

#### Release Notes:

- Added support for [LM Studio](https://lmstudio.ai/) to the Assistant.

#### Quick demo:


https://github.com/user-attachments/assets/af58fc13-1abc-4898-9747-3511016da86a

#### Future enhancements:
- wire up tool calling (new in [LM Studio
0.3.6](https://lmstudio.ai/blog/lmstudio-v0.3.6))

---------

Co-authored-by: Marshall Bowers <elliott.codes@gmail.com>

crates/language_models/src/settings.rs

@@ -14,6 +14,7 @@ use crate::provider::{
     cloud::{self, ZedDotDevSettings},
     copilot_chat::CopilotChatSettings,
     google::GoogleSettings,
+    lmstudio::LmStudioSettings,
     ollama::OllamaSettings,
     open_ai::OpenAiSettings,
 };
@@ -59,12 +60,14 @@ pub struct AllLanguageModelSettings {
     pub zed_dot_dev: ZedDotDevSettings,
     pub google: GoogleSettings,
     pub copilot_chat: CopilotChatSettings,
+    pub lmstudio: LmStudioSettings,
 }
 
 #[derive(Default, Clone, Debug, Serialize, Deserialize, PartialEq, JsonSchema)]
 pub struct AllLanguageModelSettingsContent {
     pub anthropic: Option<AnthropicSettingsContent>,
     pub ollama: Option<OllamaSettingsContent>,
+    pub lmstudio: Option<LmStudioSettingsContent>,
     pub openai: Option<OpenAiSettingsContent>,
     #[serde(rename = "zed.dev")]
     pub zed_dot_dev: Option<ZedDotDevSettingsContent>,
@@ -153,6 +156,12 @@ pub struct OllamaSettingsContent {
     pub available_models: Option<Vec<provider::ollama::AvailableModel>>,
 }
 
+#[derive(Default, Clone, Debug, Serialize, Deserialize, PartialEq, JsonSchema)]
+pub struct LmStudioSettingsContent {
+    pub api_url: Option<String>,
+    pub available_models: Option<Vec<provider::lmstudio::AvailableModel>>,
+}
+
 #[derive(Clone, Debug, Serialize, Deserialize, PartialEq, JsonSchema)]
 #[serde(untagged)]
 pub enum OpenAiSettingsContent {
@@ -278,6 +287,18 @@ impl settings::Settings for AllLanguageModelSettings {
                 ollama.as_ref().and_then(|s| s.available_models.clone()),
             );
 
+            // LM Studio
+            let lmstudio = value.lmstudio.clone();
+
+            merge(
+                &mut settings.lmstudio.api_url,
+                value.lmstudio.as_ref().and_then(|s| s.api_url.clone()),
+            );
+            merge(
+                &mut settings.lmstudio.available_models,
+                lmstudio.as_ref().and_then(|s| s.available_models.clone()),
+            );
+
             // OpenAI
             let (openai, upgraded) = match value.openai.clone().map(|s| s.upgrade()) {
                 Some((content, upgraded)) => (Some(content), upgraded),