Fix bicep test exit code on compilation errors

[πάθει κόσμος (pathei-kosmos)]

Description

bicep test used only test evaluation results to determine its exit code. Compilation errors could therefore be reported while the command still returned 0 and printed an overall success summary.

This change includes compilation errors in the exit status and suppresses the overall success summary when they are present. Per-test results remain available, so existing skipped and failed evaluation output is unchanged.

Fixes #20304.

Example Usage

For a test declaration that references a missing file, bicep test now reports BCP091 and returns exit code 1 without printing "All 0 evaluations passed".

Validation

• Added a regression test with one valid test and one missing target
• Bicep.Cli.IntegrationTests in Release: 1134 passed

Checklist

• I have read and adhere to the contribution guide.

Microsoft Reviewers: Open in CodeFlow