firefox-eme-free: Add private browsing shortcut

[jasongodev]

Add private browsing shortcut and places all shortcuts under a group folder in Scoop Apps.

Relates to #10777 Relates to #10778

• [x] I have read the Contributing Guide.

[jasongodev]

/verify

[github-actions[bot]]

All changes look good.

Wait for review from human collaborators.

firefox-eme-free

• [x] Description
• [x] License
• [x] Hashes
• [x] Checkver
• [x] Autoupdate
• [x] Autoupdate Hash Extraction