chore: Style api docs-forward tools

[pan-kot]

A follow-up for #233 (see how it is applied: https://github.com/cloudscape-design/components/pull/4901/changes#diff-d9121ef7ddab55ffde139a30ce4f5e7f2961d8450cc6b4488649863cc135eccb).

While style-api.docs(...) annotates component's own tokens, the style-api.docs-forward(...) annotates ones that point to components used via internal composition. For example, in the Alert there are two slots:

• root - alert's body, declaring style tokens such as color, background-color, and more;
• dismissButton - alert's dismiss button, which uses Button internally. The corresponding classNames.dismissButton is passed down as Button's classNames.button.

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.09%. Comparing base (d7cc26a) to head (1925f4e).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #247   +/-   ##
=======================================
  Coverage   98.09%   98.09%           
=======================================
  Files          56       56           
  Lines        1787     1788    +1     
  Branches      517      518    +1     
=======================================
+ Hits         1753     1754    +1     
+ Misses         34       33    -1     
- Partials        0        1    +1     

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