Restore last open Sketches at launch

[ubidefeo]

Describe the bug
If I have multiple Sketches open and quit the app, when I relaunch it only the last opened Sketch is the only one loaded

To Reproduce
Steps to reproduce the behavior:

1. Open a series of Sketches from the Sketchbook
2. Quit IDE
3. Launch IDE
4. Only the last Sketch opened in the last session is restored

Expected behavior
When launched, the IDE should restore all sketches windows (workspaces) which were open before last quitting the app.
If possible the location of windows should be preserved.

Screenshots

IDE2_restore-last-sketches-on-launch.mp4

Desktop (please complete the following information):

• OS: Mac OS Big Sur (11.2.3)
• Version: 2.0.0 Beta 7 (screen recording is from Beta 6 but tested on 7)