[build-tools] Load composite function catalogs for hook steps

[sswrk]

Why

Hook steps can reference local composite functions (uses: ./...), but build-tools only loaded the catalog from job steps. Hook-only refs failed at parse/runtime even when function.yml was on disk.

How

• Pass hooks into buildCompositeFunctionCatalogAsync for steps-based jobs (custom / generic), loading composites from every registered hook key (parity with built-in uses: validation).
• For native jobs, load composites only from wrapped hook keys so unwrapped keys keep warn-not-fail and do not fail catalog loading.

Test Plan

Added unit tests.

[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 legacy command/path local functions referenced from workflows #4098
• [build-tools] Load legacy command/path local functions and resolve module paths #4097
• [steps] Expand legacy command/path local functions to a single build step #4096
• [eas-build-job] Accept legacy command/path custom function shape in function.yml #4095
• [eas-cli] Validate local composite functions referenced from workflow hooks #4064
• [build-tools] Load composite function catalogs for hook steps #4063 👈 (View in Graphite)
• [steps] Support local composite functions in hook steps #4062
• [steps] Unify the default gating of steps with no if: across steps, composite scopes, and hooks #4061
• [eas-cli] Validate local composite functions in workflow files #3931
• [build-tools] Load local composite function catalog at build runtime #3930
• [steps][4/4] Resolve composite function outputs #4015
• [steps][3/4] Interpolate composite function inputs #4014
• [steps][2/4] Expand composite function references into build steps #3929 : 1 other dependent PR (#4013 )
• [steps][1/4] Add isCompositeFunctionPath and reject local composite functions in custom builds #3956
• [eas-build-job] Add local composite function schema #3928
• main

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

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 62.24%. Comparing base (72786a9) to head (aa881f7).

Additional details and impacted files

@@                                      Coverage Diff                                      @@
##           szymonswierk/eng-22387-steps-composite-functions-in-hooks    #4063      +/-   ##
=============================================================================================
+ Coverage                                                      62.23%   62.24%   +0.02%     
=============================================================================================
  Files                                                            995      995              
  Lines                                                          44764    44778      +14     
  Branches                                                        9415     9419       +4     
=============================================================================================
+ Hits                                                           27855    27869      +14     
  Misses                                                         15462    15462              
  Partials                                                        1447     1447              

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[github-actions]

✅ Thank you for adding the changelog entry!