Provide wasm extensions with APIs needed for using pre-installed LSP binaries (#9085)

In this PR, we've added two new methods that LSP extensions can call:
* `shell_env()`, for retrieving the environment variables set in the
user's default shell in the worktree
* `which(command)`, for looking up paths to an executable (accounting
for the user's shell env in the worktree)

To test this out, we moved the `uiua` language support into an
extension. We went ahead and removed the built-in support, since this
language is extremely obscure. Sorry @mikayla-maki. To continue coding
in Uiua in Zed, for now you can `Add Dev Extension` from the extensions
pane, and select the `extensions/uiua` directory in the Zed repo. Very
soon, we'll support publishing these extensions so that you'll be able
to just install it normally.

Release Notes:

- N/A

---------

Co-authored-by: Marshall <marshall@zed.dev>

crates/extension/src/extension_store.rs

@@ -193,7 +193,7 @@ impl ExtensionStore {
             extension_index: Default::default(),
             installed_dir,
             index_path,
-            builder: Arc::new(ExtensionBuilder::new(build_dir, http_client.clone())),
+            builder: Arc::new(ExtensionBuilder::new(build_dir)),
             outstanding_operations: Default::default(),
             modified_extensions: Default::default(),
             reload_complete_senders: Vec::new(),
@@ -545,7 +545,7 @@ impl ExtensionStore {
                         builder
                             .compile_extension(
                                 &extension_source_path,
-                                CompileExtensionOptions { release: true },
+                                CompileExtensionOptions { release: false },
                             )
                             .await
                     }