build: switch from yarn to npm to manage js dependencies and move js contents to root

yarn v1 is being deprecated and starts to have some issues

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

src/types/feedtoken.model.ts

@@ -0,0 +1,8 @@
+import type { IPerson } from "./actor";
+import type { ICurrentUser } from "./current-user.model";
+
+export interface IFeedToken {
+  token: string;
+  actor?: IPerson;
+  user: ICurrentUser;
+}