feat(table): implement conditional visibility for sort descending checkbox

[ffalathel]

SUMMARY

This PR implements conditional visibility for the "Sort Descending" checkbox in the Table Chart control panel, improving user experience by eliminating confusion about non-functional controls.

Key Changes:

• Conditional Visibility: The "Sort Descending" checkbox now only appears when a "Sort Query By" metric is selected, making it clear that these controls work together
• Proper Positioning: Moved the checkbox to be directly below the "Sort Query By" control in its own row for better visual hierarchy
• Fixed Sorting Logic: Resolved a default value mismatch between the control panel (default: true) and buildQuery logic (was default: false) that was preventing proper sorting functionality
• Edge Case Handling: Added comprehensive validation for null, undefined, empty string, and empty array values

Design Rationale:

• Follows established UI patterns for conditional control visibility
• Maintains backward compatibility with existing functionality
• Improves workflow efficiency by reducing unnecessary clicks
• Creates clear visual relationship between dependent controls

Before:

• "Sort Descending" checkbox always visible in aggregation mode
• Checkbox positioned far from "Sort Query By" control
• Users could interact with checkbox even when no metric was selected (non-functional)
• Sorting functionality had default value mismatch

After:

• "Sort Descending" checkbox only visible when "Sort Query By" metric is selected
• Checkbox positioned directly below "Sort Query By" control in its own row
• Clear visual relationship between dependent controls
• Proper sorting functionality with consistent default values

Screen.Recording.2025-10-19.at.20.08.12.mov

TESTING INSTRUCTIONS

1. Open Superset and create a new Table Chart
2. Switch to "Aggregate" mode
3. Verify "Sort Descending" checkbox is hidden initially (no metric selected)
4. Select a metric in "Sort Query By" dropdown
5. Verify "Sort Descending" checkbox appears directly below the dropdown
6. Verify checkbox is checked by default (descending sort)
7. Run the query and verify results are sorted in descending order
8. Uncheck the "Sort Descending" checkbox
9. Run the query and verify results are sorted in ascending order
10. Clear the metric selection
11. Verify "Sort Descending" checkbox disappears
12. Test with different metric types and edge cases (null, empty arrays, etc.)

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API