fix(plugin): check exit value when executing xcodebuild command

[buenaflor]

💡 Motivation and Context

Follow up pr of #320

[codecov]

Codecov Report

Attention: Patch coverage is 53.84615% with 6 lines in your changes missing coverage. Please review.

Project coverage is 79.75%. Comparing base (1279a73) to head (7aac04c).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
...multiplatform/gradle/DerivedDataPathValueSource.kt	53.84%	3 Missing and 3 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #326      +/-   ##
==========================================
- Coverage   80.20%   79.75%   -0.46%     
==========================================
  Files          43       43              
  Lines         793      800       +7     
  Branches      105      106       +1     
==========================================
+ Hits          636      638       +2     
- Misses        103      107       +4     
- Partials       54       55       +1     

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