Added form validation element to graphql.

Add Webform Element Validation Metadata to GraphQL Output

Summary

This PR enhances the graphql_compose_webform module by exposing validation-related properties for Webform elements in the GraphQL schema.

Changes

• Added support for the following fields:

  • counter_type
  • counter_minimum
  • counter_maximum
  • counter_maximum_message
  • pattern
  • pattern_error
  • required
  • required_error
  • unique
  • unique_entity
  • unique_user
  • unique_error

• These are resolved directly from the element render array.

Why?

This enables headless/front-end applications to apply consistent validation logic based on the Webform configuration in Drupal.

Testing

1. Create a webform with validation rules.

2. Query via GraphQL:

   {
     webform(id: "example_form") {
       elements {
         key
         counter_type
         counter_minimum
         counter_maximum
         counter_maximum_message
         pattern
         pattern_error
         required
         required_error
         unique
         unique_entity
         unique_user
         unique_error
       }
     }
   }

3. Verify returned values match the Webform config.