fix(APIKeyModal): implement focus return to generate button

[makafsal]

Closes #6246

What did you change?

Implement new property launcherButtonRef

How did you test and verify your work?

yarn test
yarn avt

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.59%. Comparing base (27fc332) to head (f8aacdf).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6440   +/-   ##
=======================================
  Coverage   79.58%   79.59%           
=======================================
  Files         394      394           
  Lines       12861    12866    +5     
  Branches     4266     4267    +1     
=======================================
+ Hits        10236    10241    +5     
  Misses       2625     2625           

Components	Coverage Δ
ibm-products	∅ <ø> (∅)
ibm-products-web-components	∅ <ø> (∅)

[davidmenendez]

LGTM!