chore: add widget-exports file to export map

[just-boris]

Description

Allow this export to be used in the widget bundle build without hacks

Related links, issue #, if available: n/a

How has this been tested?

There is a test that all public exports work: https://github.com/cloudscape-design/components/blob/main/src/__tests__/functional-tests/public-exports.test.ts

Review checklist

The following items are to be evaluated by the author(s) and the reviewer(s).

Correctness

• Changes include appropriate documentation updates.
• Changes are backward-compatible if not indicated, see CONTRIBUTING.md.
• Changes do not include unsupported browser features, see CONTRIBUTING.md.
• Changes were manually tested for accessibility, see accessibility guidelines.

Security

• If the code handles URLs: all URLs are validated through the checkSafeUrl function.

Testing

• Changes are covered with new/existing unit tests?
• Changes are covered with new/existing integration tests?

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.40%. Comparing base (1c32dd6) to head (b048287).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3173   +/-   ##
=======================================
  Coverage   96.40%   96.40%           
=======================================
  Files         784      784           
  Lines       22143    22143           
  Branches     7604     7594   -10     
=======================================
  Hits        21348    21348           
- Misses        743      788   +45     
+ Partials       52        7   -45     

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