General fixes

[Joeavaikath]

Why the changes were made

This PR improves the nonadmin backup describe command with better output formatting, bug fixes, and code quality improvements:

1. Improve nonadmin backup describe output formatting

• Aligns the nonadmin backup describe output to match the admin/Velero backup describe format for consistency
• Makes the output more readable by parsing JSON data structures and displaying them hierarchically
• Moves the Resource List to appear before Backup Volumes section (matching admin output order)
• Skips printing empty sections (no snapshots, no errors/warnings) to reduce clutter

2. Refactor download request logic to eliminate code duplication

• Consolidates duplicate download request logic into a reusable ProcessDownloadRequest function in the shared package
• Reduces code duplication across backup describe, logs, and download commands
• Improves maintainability and consistency in error handling and timeout behavior

3. Fix gzip decompression for backup downloads and enhance describe command

• Fixes gzip decompression issue when downloading backup data
• Ensures downloaded content is properly decompressed before processing
• Enhances error handling in the describe command

How to test the changes made

Prerequisites

# Create a nonadmin backup
kubectl oadp nonadmin backup create test-backup --namespace <your-namespace>

# Wait for backup to complete
kubectl oadp nonadmin backup get test-backup

Test 1: Basic describe output formatting

kubectl oadp nonadmin backup describe test-backup

Expected output:
- Clean, well-formatted output matching Velero admin backup describe style
- Resource List appears after "Items backed up" and before "Backup Volumes"
- Empty sections are not shown

Before:
Resource List:
  {"v1/ConfigMap":["namespace/config1","namespace/config2"],...}

After:
Resource List:
  v1/ConfigMap:
    - namespace/config1
    - namespace/config2
  v1/Secret:
    - namespace/secret1

Test 2: Detailed output with --details flag

kubectl oadp nonadmin backup describe test-backup --details

Expected output:
- Only non-empty sections are displayed (Volume Snapshot Details, Backup Results, Item Operations)
- Backup Results shows separated Errors and Warnings subsections
- JSON data is formatted and indented for readability
- Empty arrays/objects result in section being skipped entirely

Test 3: Download and logs commands (refactoring verification)

# Test download still works with refactored code
kubectl oadp nonadmin backup download test-backup BackupLog

# Test logs command
kubectl oadp nonadmin backup logs test-backup

Expected output:
- Downloads complete successfully with proper gzip decompression
- Logs are displayed correctly
- No regression in functionality

Visual Comparison

Compare the output to admin backup describe:
# Admin backup describe (for reference)
velero backup describe <backup-name> --details

# Nonadmin backup describe (should look similar)
kubectl oadp nonadmin backup describe test-backup --details

The nonadmin output should now closely match the admin format, making it easier for users familiar with Velero to understand the nonadmin interface.