Fix skip-forward button accessibility issue

[tsi]

Description

Got a complaint from a customer about the Wave tool being mad at some empty button.
Somehow the skip-backward button does have a default controlText. only the forward one was missing it.

Specific Changes proposed

Add a default controlText for the button component

Requirements Checklist

• Feature implemented / Bug fixed
• If necessary, more likely in a feature request than a bug fix
  • Change has been verified in an actual browser (Chrome, Firefox, IE)
  • Unit Tests updated or fixed
  • Docs/guides updated
  • Example created (starter template on JSBin)
• Reviewed by Two Core Contributors

Before	After

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (d2dc5b9) 82.65% compared to head (61e7781) 82.65%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #8532   +/-   ##
=======================================
  Coverage   82.65%   82.65%           
=======================================
  Files         113      113           
  Lines        7605     7606    +1     
  Branches     1828     1828           
=======================================
+ Hits         6286     6287    +1     
  Misses       1319     1319           

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