Add fail-continue Export Option to ExportContentletProcessor

[jgambarios]

Parent Issue

#30557

Task

Add support for a fail-continue option in ExportContentletProcessor to control how export handles errors during content processing.

Tasks:

1. Add fail-continue parameter to export job parameters
2. Implement error handling logic:

• For fail-continue=true: log error and continue processing
• For fail-continue=false: stop export on first error

3. Track failed items regardless of fail-continue setting
4. Add error summary to job result metadata:

• Number of failed items
• Error details per failed item
• Total processed vs failed items

5. Update tests

Proposed Objective

Core Features

Proposed Priority

Priority 2 - Important

Acceptance Criteria

• Export respects fail-continue parameter
• All errors are tracked and reported in job result
• Error details include:
  • Content identifier
  • Error message
  • Stack trace for debugging
• Export progress accurately reflects skipped/failed items
• Tests cover both fail-continue modes