Extract PHP support into an extension (#9966)

This PR extracts PHP support into an extension and removes the built-in
PHP support from Zed.

There's a small workaround necessary in order for us to provide the
`language_ids` on the `LspAdapter` that are needed for the language
server to run properly. Eventually we'll want to build this into the
extension API, but for now we're just hard-coding it on the host side.

Release Notes:

- Removed built-in support for PHP, in favor of making it available as
an extension. The PHP extension will be suggested for download when you
open a `.php` file.

crates/extension/src/extension_lsp_adapter.rs

@@ -1,6 +1,7 @@
 use crate::wasm_host::{wit::LanguageServerConfig, WasmExtension, WasmHost};
 use anyhow::{anyhow, Context, Result};
 use async_trait::async_trait;
+use collections::HashMap;
 use futures::{Future, FutureExt};
 use gpui::AsyncAppContext;
 use language::{Language, LanguageServerName, LspAdapter, LspAdapterDelegate};
@@ -106,6 +107,17 @@ impl LspAdapter for ExtensionLspAdapter {
         None
     }
 
+    fn language_ids(&self) -> HashMap<String, String> {
+        // TODO: Eventually we'll want to expose an extension API for doing this, but for
+        // now we just manually language ID mappings for extensions that we know need it.
+
+        if self.extension.manifest.id.as_ref() == "php" {
+            return HashMap::from_iter([("PHP".into(), "php".into())]);
+        }
+
+        Default::default()
+    }
+
     async fn initialization_options(
         self: Arc<Self>,
         delegate: &Arc<dyn LspAdapterDelegate>,