Fluentui: Pivot: IPivotProps style function never gets applied

[helenanderson]

Bug Report

• __Package version(s)__: 5.112.0
• __Browser and OS versions__: (fill this out if relevant)

Priorities and help requested (not applicable if asking question):

Are you willing to submit a PR to fix? TBD

Requested priority: (Blocking, High, Normal, Low)

Products/sites affected: (if applicable)

Describe the issue:

The Pivot component has a styles prop (or getStyles, on older versions), but when I specify a style function for that prop, my styles don't get applied to the Pivot. Digging into Pivot.base.tsx, it looks like this prop is never actually used.

I looked through some of the history and couldn't tell if this was known feature work that's on the backlog, or if this should be treated as a new bug.

Actual behavior:

Expected behavior:

If applicable, please provide a codepen repro:

[JasonGore]

Pivot conversion to JS styling was only partially imlemented via #4656. It will be finished soon.