chore: Editor 'plugin' -> 'extension'

They've always been called extensions, not sure why the folder was plugins. Part of ongoing spring cleaning

app/multiplayer/MultiplayerExtension.ts

@@ -1,56 +0,0 @@
-import {
-  ySyncPlugin,
-  yCursorPlugin,
-  yUndoPlugin,
-  undo,
-  redo,
-} from "@getoutline/y-prosemirror";
-import { keymap } from "prosemirror-keymap";
-import * as Y from "yjs";
-import { Extension } from "~/editor";
-
-export default class MultiplayerExtension extends Extension {
-  get name() {
-    return "multiplayer";
-  }
-
-  get plugins() {
-    const { user, provider, document: doc } = this.options;
-    const type = doc.get("default", Y.XmlFragment);
-
-    const assignUser = (tr: Y.Transaction) => {
-      const clientIds = Array.from(doc.store.clients.keys());
-
-      if (
-        tr.local &&
-        tr.changed.size > 0 &&
-        !clientIds.includes(doc.clientID)
-      ) {
-        const permanentUserData = new Y.PermanentUserData(doc);
-        permanentUserData.setUserMapping(doc, doc.clientID, user.id);
-        doc.off("afterTransaction", assignUser);
-      }
-    };
-
-    // only once we have authenticated successfully do we initalize awareness.
-    // we could send this earlier, but getting authenticated faster is more important
-    provider.on("authenticated", () => {
-      provider.setAwarenessField("user", user);
-    });
-
-    // only once an actual change has been made do we add the userId <> clientId
-    // mapping, this avoids stored mappings for clients that never made a change
-    doc.on("afterTransaction", assignUser);
-
-    return [
-      ySyncPlugin(type),
-      yCursorPlugin(provider.awareness),
-      yUndoPlugin(),
-      keymap({
-        "Mod-z": undo,
-        "Mod-y": redo,
-        "Mod-Shift-z": redo,
-      }),
-    ];
-  }
-}

app/scenes/Document/components/MultiplayerEditor.tsx

@@ -5,6 +5,7 @@ import { useTranslation } from "react-i18next";
 import { useHistory } from "react-router-dom";
 import { IndexeddbPersistence } from "y-indexeddb";
 import * as Y from "yjs";
+import MultiplayerExtension from "@shared/editor/extensions/Multiplayer";
 import Editor, { Props as EditorProps } from "~/components/Editor";
 import env from "~/env";
 import useCurrentToken from "~/hooks/useCurrentToken";
@@ -14,7 +15,6 @@ import useIsMounted from "~/hooks/useIsMounted";
 import usePageVisibility from "~/hooks/usePageVisibility";
 import useStores from "~/hooks/useStores";
 import useToasts from "~/hooks/useToasts";
-import MultiplayerExtension from "~/multiplayer/MultiplayerExtension";
 import Logger from "~/utils/Logger";
 import { supportsPassiveListener } from "~/utils/browser";
 import { homePath } from "~/utils/routeHelpers";