debugger beta: Fix dap_schema for DAP extensions (#31173)

We now actually call dap_schema provided by extensions instead of
defaulting to a null `serde_json::Value`. We still need to update the
Json LSP whenever a new dap is installed.

Release Notes:

- N/A

crates/dap/src/registry.rs

@@ -64,13 +64,16 @@ impl DapRegistry {
         );
     }
 
-    pub fn adapters_schema(&self) -> task::AdapterSchemas {
+    pub async fn adapters_schema(&self) -> task::AdapterSchemas {
         let mut schemas = AdapterSchemas(vec![]);
 
-        for (name, adapter) in self.0.read().adapters.iter() {
+        // Clone to avoid holding lock over await points
+        let adapters = self.0.read().adapters.clone();
+
+        for (name, adapter) in adapters.into_iter() {
             schemas.0.push(AdapterSchema {
-                adapter: name.clone().into(),
-                schema: adapter.dap_schema(),
+                adapter: name.into(),
+                schema: adapter.dap_schema().await,
             });
         }