Use Extension trait in ExtensionLspAdapter (#20704)

This PR updates the `ExtensionLspAdapter` to go through the `Extension`
trait for interacting with extensions rather than going through the
`WasmHost` directly.

Release Notes:

- N/A

crates/extension/src/extension.rs

@@ -1,17 +1,20 @@
 pub mod extension_builder;
 mod extension_manifest;
-mod slash_command;
+mod types;
 
 use std::path::{Path, PathBuf};
 use std::sync::Arc;
 
+use ::lsp::LanguageServerName;
 use anyhow::{anyhow, bail, Context as _, Result};
 use async_trait::async_trait;
+use fs::normalize_path;
 use gpui::Task;
+use language::LanguageName;
 use semantic_version::SemanticVersion;
 
 pub use crate::extension_manifest::*;
-pub use crate::slash_command::*;
+pub use crate::types::*;
 
 #[async_trait]
 pub trait WorktreeDelegate: Send + Sync + 'static {
@@ -34,6 +37,43 @@ pub trait Extension: Send + Sync + 'static {
     /// Returns the path to this extension's working directory.
     fn work_dir(&self) -> Arc<Path>;
 
+    /// Returns a path relative to this extension's working directory.
+    fn path_from_extension(&self, path: &Path) -> PathBuf {
+        normalize_path(&self.work_dir().join(path))
+    }
+
+    async fn language_server_command(
+        &self,
+        language_server_id: LanguageServerName,
+        language_name: LanguageName,
+        worktree: Arc<dyn WorktreeDelegate>,
+    ) -> Result<Command>;
+
+    async fn language_server_initialization_options(
+        &self,
+        language_server_id: LanguageServerName,
+        language_name: LanguageName,
+        worktree: Arc<dyn WorktreeDelegate>,
+    ) -> Result<Option<String>>;
+
+    async fn language_server_workspace_configuration(
+        &self,
+        language_server_id: LanguageServerName,
+        worktree: Arc<dyn WorktreeDelegate>,
+    ) -> Result<Option<String>>;
+
+    async fn labels_for_completions(
+        &self,
+        language_server_id: LanguageServerName,
+        completions: Vec<Completion>,
+    ) -> Result<Vec<Option<CodeLabel>>>;
+
+    async fn labels_for_symbols(
+        &self,
+        language_server_id: LanguageServerName,
+        symbols: Vec<Symbol>,
+    ) -> Result<Vec<Option<CodeLabel>>>;
+
     async fn complete_slash_command_argument(
         &self,
         command: SlashCommand,
@@ -44,7 +84,7 @@ pub trait Extension: Send + Sync + 'static {
         &self,
         command: SlashCommand,
         arguments: Vec<String>,
-        resource: Option<Arc<dyn WorktreeDelegate>>,
+        worktree: Option<Arc<dyn WorktreeDelegate>>,
     ) -> Result<SlashCommandOutput>;
 
     async fn suggest_docs_packages(&self, provider: Arc<str>) -> Result<Vec<String>>;