Joh/ministerial-swan (#212096)

* first cut of embeddings API

https://github.com/microsoft/vscode/issues/212083

* add event

* fix tests

extensions/vscode-api-tests/package.json

@@ -19,6 +19,7 @@
     "documentFiltersExclusive",
     "documentPaste",
     "editorInsets",
+    "embeddings",
     "extensionRuntime",
     "extensionsAny",
     "externalUriOpener",
@@ -80,7 +81,7 @@
         "id": "api-test.participant2",
         "name": "participant2",
         "description": "test",
-        "commands": [ ]
+        "commands": []
       }
     ],
     "configuration": {