Advanced Button settings are not subtoggle enabeld

[xxtesaxx]

Problem Description

While it is possible to give the advanced button settings a custom tab and toggle slug, you can't use a subtoggle which would be especially nice if you have two or more buttons on a module or two buttons and some general button related settings which you could display in a third subtoggle.

[etstaging]

QA Checklist

Reporter

• [ ] Helpful title used  
  • Helpful title format: Scope(s) :: One Sentence To Describe The Issue
  • Example: VB :: Floating Toolbar :: Jumps To Top Of Page
• [ ] Detailed description
  • Description should usually be 150+ characters.
• [ ] Steps to reproduce included
• [ ] Support Ticket URL included
• [ ] Image and/or gif

Developer

• [ ] Steps to reproduce proven solved
• [ ] Test included and coverage acceptable and all Tests passing?
• [ ] PR description has layman's description of problem and solution and "Areas Affected" listed/explained?
• [ ] PR branch includes latest commits from master branch (at the time of checking)?
• [ ] Estimated points on issue
• [ ] Proper code documentation and conventions?
• [ ] Proper RTL appearance
• [ ] i18n used if applicable
• [ ] Ajax/Form used? Nonce used? Perms checked? All user input sanitized and validated? Intentional unsanitized/unescaped functions used?
• [ ] Database saved/updated? Data sanitized and validated?
• [ ] Variable output properly escaped and validated?

Peer Review

• [ ] PR branch includes latest commits from master branch (at the time of checking)?
• [ ] Steps to reproduce proven solved
• [ ] Affected areas are tested and ok
• [ ] Proper code documentation and conventions
• [ ] Proper RTL appearance
• [ ] i18n used if applicable
• [ ] Test(s) included and coverage acceptable
• [ ] Ajax/Form used? Nonce used? Perms checked? All user input sanitized and validated? Intentional unsanitized/unescaped functions used?
• [ ] Database saved/updated? Data sanitized and validated?
• [ ] Variable output properly escaped and validated?

Quality Assurance

• [ ] All tests passed on CircleCI.
• [ ] Steps to reproduce passed, the fix works.
• [ ] No errors in console or output
• [ ] Affected areas are tested and ok
• [ ] The fix does not change a customer's website in any surprising or unintended way
  • [ ] If Divi's design is adjusted, settings are migrated gracefully and invisibly

Design Review

• [ ] UI is to spec
• [ ] UX is to spec
• [ ] Design is to spec
• [ ] No surprising visual changes to a customer's website will be experienced after updating
  • [ ] Any/all visual changes are migrated gracefully

Dev Review

• [ ] Test(s) included and coverage acceptable
• [ ] Ajax/Form used? Nonce used? Perms checked? All user input sanitized and validated? Intentional unsanitized/unescaped functions used?
• [ ] Database saved/updated? Data sanitized and validated?
• [ ] Variable output properly escaped and validated?
• [ ] i18n used if applicable
• [ ] Implementation acceptable, DRY, Scaleable, future safe
• [ ] Best practices used, cleverness and grokage, ES6 use, etc.