Refactor builder to embed Object validation create/delete/update (#13934)

# Introduction
Moving validation directly in the builder that has the perfect
granularity to do it.
When importing we won't have to infer and dispatch on the operation
nature ( update delete create ) and validate accordingly

## Objects
Only migrated object validation for the moment even though create object
involves a validate flat field metadata creation call too

## TODO
- improve `otherFlatObjectMetadataMapsToValidate` naming too vague

## Next
- handle fields validation within fields actions build
- Unit test coverage validation issue on builder and validate
- integration test plugging with new feature flag

## Manual tested
- Update
- Delete
- Create TODO

packages/twenty-server/src/engine/metadata-modules/flat-object-metadata/validators/utils/validate-flat-object-metadata-identifiers.util.ts

@@ -19,12 +19,12 @@ export const validateFlatObjectMetadataIdentifiers = (
     flatObjectMetadata;
 
   if (isDefined(labelIdentifierFieldMetadataId)) {
-    const relatedFlatFieldMetadata = flatObjectMetadata.flatFieldMetadatas.find(
+    const flatFieldMetadata = flatObjectMetadata.flatFieldMetadatas.find(
       (flatFieldMetadata) =>
         flatFieldMetadata.id === labelIdentifierFieldMetadataId,
     );
 
-    if (!isDefined(relatedFlatFieldMetadata)) {
+    if (!isDefined(flatFieldMetadata)) {
       errors.push(
         new ObjectMetadataException(
           'labelIdentifierFieldMetadataId validation failed: related field metadata not found',
@@ -34,9 +34,7 @@ export const validateFlatObjectMetadataIdentifiers = (
           },
         ),
       );
-    } else if (
-      !isLabelIdentifierFieldMetadataTypes(relatedFlatFieldMetadata.type)
-    ) {
+    } else if (!isLabelIdentifierFieldMetadataTypes(flatFieldMetadata.type)) {
       errors.push(
         new ObjectMetadataException(
           'labelIdentifierFieldMetadataId validation failed: field type not compatible',