Add missing BuildNumber to CodeBuildEventAdditionalInformation

[guiminyao]

Issue #, if available:
#413

Description of changes:
Add missing BuildNumber to CodeBuildEventAdditionalInformation struct, and update tests.
SUCCEEDED, FAILED, STOPPED events do have the piece of info, not presented in IN_PROGRESS event.

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[codecov-commenter]

Codecov Report

Merging #417 (24be98f) into main (3afc312) will decrease coverage by 0.23%.
The diff coverage is 44.44%.

@@            Coverage Diff             @@
##             main     #417      +/-   ##
==========================================
- Coverage   71.66%   71.42%   -0.24%     
==========================================
  Files          19       19              
  Lines        1041     1050       +9     
==========================================
+ Hits          746      750       +4     
- Misses        228      232       +4     
- Partials       67       68       +1     

Impacted Files	Coverage Δ
events/codebuild.go	40.90% <44.44%> (+2.44%)	⬆️

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