Form Module Improvements - Bulk import for option lists (checkbox, dropdown, radio, tree)

Problem: Manual option entry is slow.

Actionables:

• Support CSV/paste import with columns: label, value, group (optional).

• Validate duplicates; provide merge/replace modes.

Success criteria:

• Admin can import hundreds of options reliably; errors reported clearly.

Context: This proposal is part of the broader storyline AM-I-856.