Morph relation field v2 fixes (#14216)

Fixes, depending on the contextual current operation in order to
retrieve relation target and all morph related fields to be delete:
- DELETE Field,
- DELETE Object, 
- UPDATE Field, that affects all others related fields

packages/twenty-server/src/engine/metadata-modules/flat-field-metadata/services/flat-field-metadata-validator.service.ts

@@ -133,7 +133,7 @@ export class FlatFieldMetadataValidatorService {
       validationResult.errors.push(
         ...validateFlatFieldMetadataName(updatedFlatFieldMetadata.name),
         ...validateFlatFieldMetadataNameAvailability({
-          name: updatedFlatFieldMetadata.name,
+          flatFieldMetadata: updatedFlatFieldMetadata,
           flatObjectMetadata: flatObjectMetadata,
         }),
       );
@@ -298,7 +298,7 @@ export class FlatFieldMetadataValidatorService {
 
       validationResult.errors.push(
         ...validateFlatFieldMetadataNameAvailability({
-          name: flatFieldMetadataToValidate.name,
+          flatFieldMetadata: flatFieldMetadataToValidate,
           flatObjectMetadata: parentFlatObjectMetadata,
         }),
       );