Add initial support for defining language server adapters in WebAssembly-based extensions (#8645)

This PR adds **internal** ability to run arbitrary language servers via
WebAssembly extensions. The functionality isn't exposed yet - we're just
landing this in this early state because there have been a lot of
changes to the `LspAdapter` trait, and other language server logic.

## Next steps

* Currently, wasm extensions can only define how to *install* and run a
language server, they can't yet implement the other LSP adapter methods,
such as formatting completion labels and workspace symbols.
* We don't have an automatic way to install or develop these types of
extensions
* We don't have a way to package these types of extensions in our
extensions repo, to make them available via our extensions API.
* The Rust extension API crate, `zed-extension-api` has not yet been
published to crates.io, because we still consider the API a work in
progress.

Release Notes:

- N/A

---------

Co-authored-by: Marshall <marshall@zed.dev>
Co-authored-by: Nathan <nathan@zed.dev>
Co-authored-by: Marshall Bowers <elliott.codes@gmail.com>

crates/prettier/src/prettier.rs

@@ -2,7 +2,7 @@ use anyhow::Context;
 use collections::{HashMap, HashSet};
 use fs::Fs;
 use gpui::{AsyncAppContext, Model};
-use language::{language_settings::language_settings, Buffer, Diff};
+use language::{language_settings::language_settings, Buffer, Diff, LanguageRegistry};
 use lsp::{LanguageServer, LanguageServerId};
 use node_runtime::NodeRuntime;
 use serde::{Deserialize, Serialize};
@@ -25,6 +25,7 @@ pub struct RealPrettier {
     default: bool,
     prettier_dir: PathBuf,
     server: Arc<LanguageServer>,
+    language_registry: Arc<LanguageRegistry>,
 }
 
 #[cfg(any(test, feature = "test-support"))]
@@ -155,6 +156,7 @@ impl Prettier {
         _: LanguageServerId,
         prettier_dir: PathBuf,
         _: Arc<dyn NodeRuntime>,
+        _: Arc<LanguageRegistry>,
         _: AsyncAppContext,
     ) -> anyhow::Result<Self> {
         Ok(Self::Test(TestPrettier {
@@ -168,6 +170,7 @@ impl Prettier {
         server_id: LanguageServerId,
         prettier_dir: PathBuf,
         node: Arc<dyn NodeRuntime>,
+        language_registry: Arc<LanguageRegistry>,
         cx: AsyncAppContext,
     ) -> anyhow::Result<Self> {
         use lsp::LanguageServerBinary;
@@ -206,6 +209,7 @@ impl Prettier {
         Ok(Self::Real(RealPrettier {
             server,
             default: prettier_dir == DEFAULT_PRETTIER_DIR.as_path(),
+            language_registry,
             prettier_dir,
         }))
     }
@@ -223,10 +227,12 @@ impl Prettier {
                         let buffer_language = buffer.language();
                         let parser_with_plugins = buffer_language.and_then(|l| {
                             let prettier_parser = l.prettier_parser_name()?;
-                            let mut prettier_plugins = l
-                                .lsp_adapters()
+                            let mut prettier_plugins = local
+                                .language_registry
+                                .lsp_adapters(l)
                                 .iter()
                                 .flat_map(|adapter| adapter.prettier_plugins())
+                                .copied()
                                 .collect::<Vec<_>>();
                             prettier_plugins.dedup();
                             Some((prettier_parser, prettier_plugins))
@@ -264,7 +270,7 @@ impl Prettier {
 
                                 let mut plugins = plugins
                                     .into_iter()
-                                    .filter(|&&plugin_name| {
+                                    .filter(|&plugin_name| {
                                         if plugin_name == TAILWIND_PRETTIER_PLUGIN_PACKAGE_NAME {
                                             add_tailwind_back = true;
                                             false