Fix bug when changing from string to null in forms

[Irozuku]

This pull request refactors the FormSchemaFieldWithOptions.jsx component to optimize how the JSON schema for form fields is computed and to fix a re-render loop bug that occurred when switching parameter types.

Bug Description & Reproduction Steps

Previously, the paramJsonSchema object was created inline inside fieldProps, which meant a new object reference was generated on every render. This caused the useEffect that depended on fieldProps.paramJsonSchema to run unnecessarily, even when nothing semantically changed.

This became a problem when multiple parameters had validation errors:

1. Go to the PCA converter settings.
2. Change the first parameter (N Components) to string, triggering a "required" error.
3. Change the parameter back to null.
4. Scroll down to Power Iteration Normalization, change it to null, and then back to string.
5. At this point, the parameters list would enter an infinite re-render loop.

Why It Happened

• Each re-render created a new paramJsonSchema object.
• This triggered the useEffect validator again, which called handleSetError.
• Calling handleSetError caused the parent list of parameters to re-render.
• The cycle repeated as the newly rendered components generated new schema objects, retriggering validation continuously.

Fix

• Wrapped the creation of paramJsonSchema in a useMemo hook, with dependencies [title, description, required, options, selectedType].
• This ensures that paramJsonSchema retains the same reference unless one of its dependencies actually changes, breaking the re-render loop and significantly improving performance.

Performance and React Optimization

• Avoids unnecessary useEffect executions on every render.
• Prevents infinite re-renders when toggling parameter types with active validation errors.
• Improves rendering efficiency by reducing object churn in fieldProps.