Add 'Save' Button to Personal Lighting Floater.

[canny]

Add a save button to the personal lighting floater so users can save the current personal lighting settings as an enviroment setting.

https://secondlife.canny.io/admin/feedback/feature-requests/p/add-save-button-to-personal-lighting-floater

[canny]

This issue has been linked to a Canny post: Add 'Save' Button to Personal Lighting Floater. 🎉