Add stable-diffusion example using panel

[sandhujasmine]

Outstanding items:

• working through M1;
• test on CPU only
• review, get feedback, cleanup (repeat)
• history of thumbnails should be clickable. Thanks @philippjfr & @maximlt - still working on getting the updates in.
• Verify it works on the Mac using CPUs. It currently won't work without GPUs so needs to be updated to check for it. Notebook runs on the mac but does not produce images (couldn't get accelerate package working yet)
• Option to have side bar squashed by default (Panel#2410).

Nice to have / future work:

- [ ] Still seeing it stop on the GPU (investigate the collected data to see if we have a memory issue?) Wont fix (This is intermittent, running on a dev environment. Not sure this is a real problem)
- [ ] create / share punchlist of items before we can mark this done. Probably won't deploy on GPUs so leave for now

[maximlt]

I've added some comments, before I can point you to the updated docs :)

[maximlt]

@sandhujasmine I did a few changes on the branch, mostly to get the project validated and to get it to be tested and built using the macos runner, that has more memory than the ubuntu ones which were failing because of that.