[eas-cli] add --repack flag to eas build command

[szdziedzic]

Why

Add the --repack flag to the eas build command. This flag is not intended to be user-facing, it's just for us to test the onboarding repack flow

How

Add hidden --repack flag to eas build command. If the flag is used run build as custom with __eas/repack.yml config

Test Plan

test manually

[github-actions]

Size Change: +1.41 kB (0%)

Total Size: 51.3 MB

Filename	Size	Change
./packages/eas-cli/dist/eas-linux-x64.tar.gz	51.3 MB	+1.41 kB (0%)

_{compressed-size-action}

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 53.45%. Comparing base (ca803ee) to head (eb2bde1).

❗ Current head eb2bde1 differs from pull request most recent head e9acfce

Please upload reports for the commit e9acfce to get more accurate results.

Files	Patch %	Lines
packages/eas-cli/src/build/ios/prepareJob.ts	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2384      +/-   ##
==========================================
- Coverage   53.46%   53.45%   -0.00%     
==========================================
  Files         530      530              
  Lines       19504    19505       +1     
  Branches     3959     3960       +1     
==========================================
  Hits        10425    10425              
- Misses       8327     8328       +1     
  Partials      752      752              

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[github-actions]

⏩ The changelog entry check has been skipped since the "no changelog" label is present.