[Pension and Burial] More descriptive error messaging for upload errors

[matt4su]

Issue Description

As an applicant that uploading supplemental documents to the Pension or Burial application, I want descriptive error messaging that indicates specifically why the upload failed so that I may better understand the failure reason and potentially take corrective action.

Related ticket: Pension + Burial | Validate evidence documents at upload

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Tasks

• [ ] Identify the set of failure reasons that could generate an error
• [ ] Product/Design to provide approved message text for the reasons
• [ ] Implement the more descriptive reason text for each error type identified

Acceptance Criteria

• [ ] The more descriptive reason text is implemented for each error type identified in the 527 and 530

• [ ] Implementation meets VA Design System and CAIA standards