Consider adding menubar and toolbar to fieldset

[scottaohara]

Semantically being groupings of related controls, it makes sense that a fieldset would allow for these roles that have a similar purpose.

Additionally, at least with some quick testing, a legend within a fieldset with one of these roles would allow a naming mechanism without use of aria-label or aria-labelledby. Would want to test this more, but would expect similar results to #350

[scottaohara]

test cases and notes on behaviors - https://codepen.io/scottohara/pen/ExpaeEj

outside of some minor oddities with Safari/VO (bug filed for iOS), it seems to me that fieldset should allow the following roles:

• toolbar
• menubar
• menu
• listbox
• tablist
• article
• dialog
• region (this is the role that has the most odd behaviors with it, but none of which are going to cause blocking issues, and further modifications could mitigate them entirely - e.g., not using legend to attempt to name the element).