refactor(editor): ♻️ Undo / Redo buttons + structure refacto

Yet another huge refacto... While implementing undo and redo features I understood that I updated the stored typebot too many times (i.e. on each key input) so I had to rethink it entirely. I also moved around some files.

packages/models/src/utils.ts

@@ -1 +1,3 @@
 export type Table<T> = { byId: { [key: string]: T }; allIds: string[] }
+
+export const defaultTable = { byId: {}, allIds: [] }