fix: allow required fields with admin.condition in typescriptSchema

[MurzNN]

What?

Added support for marking fields as required in TypeScript schema generation when both required: true and admin.condition are defined. Updated the field requirement check in configToJSONSchema() to explicitly validate the field.required property, and added comprehensive test coverage to validate the fix.

Why?

Fields configured with required: true and admin.condition were being incorrectly excluded from the required array during TypeScript type generation. This caused TypeScript to infer these fields as optional (field?) even though they were explicitly marked as required in the configuration, resulting in type mismatches and potential runtime errors.

How?

Core Fix (configToJSONSchema.ts):

• Modified the field requirement check to include an explicit field.required === true condition alongside existing checks (isRequired and fieldSchema.required === true)
• This allows fields with admin.condition to be included in the required array when they have required: true

Test Coverage (types):

• Refactored integration tests to call configToJSONSchema() directly at runtime instead of reading pre-generated type files
• Added three new integration tests that validate: (1) field appears in required array, (2) field maintains correct type and required status, (3) no regression to other required fields
• Added four new type validation tests using tstyche framework to verify TypeScript types are correct
• All tests validate actual schema generation behavior and fail when the fix is reverted

Related Issues

Fixes #16797

[MurzNN]

Simplified and cleaned up tests, review please.