[steps] Expand custom actions at parse time

[sswrk]

Why

Please describe the motivation for this PR, and link to relevant GitHub issues, forums posts, or feature requests.

How

How did you build this feature or fix this bug and why?

Test Plan

Please describe how you tested this change and how a reviewer could reproduce your test, especially if this PR does not include automated tests! If possible, please also provide terminal output and/or screenshots demonstrating your test/reproduction.

[linear-code]

ENG-22387

[sswrk]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• [eas-cli] Validate custom actions in workflow files #3931
• [build-tools] Load custom action catalog at build runtime #3930
• [steps] Expand custom actions at parse time #3929 👈 (View in Graphite)
• [eas-build-job] Add custom action schema and utils #3928
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.

[github-actions]

❌ It looks like a changelog entry is missing for this PR. Add it manually to CHANGELOG.md.
⏩ If this PR doesn't require a changelog entry, such as if it's an internal change that doesn't affect the user experience, you can add the "no changelog" label to the PR.

[codecov]

Codecov Report

❌ Patch coverage is 94.69697% with 14 lines in your changes missing coverage. Please review.
✅ Project coverage is 59.52%. Comparing base (ff953ae) to head (56ee52f).

Files with missing lines	Patch %	Lines
packages/steps/src/utils/actionInterpolation.ts	90.25%	8 Missing ⚠️
packages/steps/src/ActionExpander.ts	97.21%	3 Missing and 1 partial ⚠️
packages/steps/src/StepsConfigParser.ts	94.12%	1 Missing ⚠️
packages/steps/src/utils/step.ts	92.31%	1 Missing ⚠️

Additional details and impacted files

@@                                     Coverage Diff                                      @@
##           szymonswierk/eng-22387-eas-build-job-local-action-schema    #3929      +/-   ##
============================================================================================
+ Coverage                                                     59.30%   59.52%   +0.22%     
============================================================================================
  Files                                                           936      939       +3     
  Lines                                                         41147    41393     +246     
  Branches                                                       8667     8743      +76     
============================================================================================
+ Hits                                                          24400    24634     +234     
- Misses                                                        16653    16664      +11     
- Partials                                                         94       95       +1     

☔ View full report in Codecov by Harness.
📢 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.