Expose keyCodeToString in lib/keys

[mkslanc]

Issue #, if available: #5706

Description of changes:

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

Pull Request Checklist:

• No backwards incompatible changes were made to Ace's public interface which is defined through the main typings file (ace.d.ts) and its references:
  • https://github.com/ajaxorg/ace/blob/master/ace.d.ts
  • https://github.com/ajaxorg/ace/blob/master/ace-modes.d.ts
  • https://github.com/ajaxorg/ace/blob/master/ace-extensions.d.ts

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.24%. Comparing base (c41e5be) to head (f355ed7).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5783      +/-   ##
==========================================
+ Coverage   87.20%   87.24%   +0.04%     
==========================================
  Files         603      604       +1     
  Lines       44236    44305      +69     
  Branches     7254     7265      +11     
==========================================
+ Hits        38574    38656      +82     
+ Misses       5662     5649      -13     

Flag	Coverage Δ
unittests	87.24% <ø> (+0.04%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.