extension: Add support for additional_workspace_configuration and additional_initialization_options (#27407)

Closes #22410

With this PR extensions can provide additional workspace configuration
for other LSP Adapters. This allows extensions like Astro, Svelte, Vue,
etc to provide plugins for vtsls typescript server, fixing issues like:
https://github.com/zed-industries/zed/issues/4577,
https://github.com/zed-industries/zed/issues/21697,
https://github.com/zed-industries/zed/issues/26901#issuecomment-2737485096

Todo:

- [x] Test case when extension is installed, does vtsls workspace config
refreshes?

Before:
<img width="450" alt="image"
src="https://github.com/user-attachments/assets/f242167c-5264-44ab-b5a7-8c90eb75c6a1"
/>

After:
<img width="450" alt="image"
src="https://github.com/user-attachments/assets/6a5f1afe-a0e1-4f64-8a95-919b0bf97614"
/>

Release Notes:

- N/A

crates/language_extension/src/extension_lsp_adapter.rs

@@ -267,6 +267,58 @@ impl LspAdapter for ExtensionLspAdapter {
         })
     }
 
+    async fn additional_initialization_options(
+        self: Arc<Self>,
+        target_language_server_id: LanguageServerName,
+        _: &dyn Fs,
+        delegate: &Arc<dyn LspAdapterDelegate>,
+    ) -> Result<Option<serde_json::Value>> {
+        let delegate = Arc::new(WorktreeDelegateAdapter(delegate.clone())) as _;
+        let json_options: Option<String> = self
+            .extension
+            .language_server_additional_initialization_options(
+                self.language_server_id.clone(),
+                target_language_server_id.clone(),
+                delegate,
+            )
+            .await?;
+        Ok(if let Some(json_options) = json_options {
+            serde_json::from_str(&json_options).with_context(|| {
+                format!(
+                    "failed to parse additional_initialization_options from extension: {json_options}"
+                )
+            })?
+        } else {
+            None
+        })
+    }
+
+    async fn additional_workspace_configuration(
+        self: Arc<Self>,
+        target_language_server_id: LanguageServerName,
+        _: &dyn Fs,
+        delegate: &Arc<dyn LspAdapterDelegate>,
+        _: Arc<dyn LanguageToolchainStore>,
+        _cx: &mut AsyncApp,
+    ) -> Result<Option<serde_json::Value>> {
+        let delegate = Arc::new(WorktreeDelegateAdapter(delegate.clone())) as _;
+        let json_options: Option<String> = self
+            .extension
+            .language_server_additional_workspace_configuration(
+                self.language_server_id.clone(),
+                target_language_server_id.clone(),
+                delegate,
+            )
+            .await?;
+        Ok(if let Some(json_options) = json_options {
+            serde_json::from_str(&json_options).with_context(|| {
+                format!("failed to parse additional_workspace_configuration from extension: {json_options}")
+            })?
+        } else {
+            None
+        })
+    }
+
     async fn labels_for_completions(
         self: Arc<Self>,
         completions: &[lsp::CompletionItem],