feat: third-party embeds (#423)

* wip

* Add more providers

* icons

* unify embed providers (Youtube)

* fix case

* YT music

* remove redundant code

packages/editor-ext/src/index.ts

@@ -14,4 +14,5 @@ export * from "./lib/attachment";
 export * from "./lib/custom-code-block"
 export * from "./lib/drawio";
 export * from "./lib/excalidraw";
+export * from "./lib/embed";