Add applicationId to syncableEntity and fix syncApp deletion (#15170)

## Context
- All flatEntity should extend SyncableEntity
- SyncableEntity should now have applicationId and application relation
- Fix syncApp deletion, should now properly use migration v2 to delete
syncable entities

packages/twenty-server/src/engine/metadata-modules/flat-object-metadata/utils/from-create-object-input-to-flat-object-metadata-and-flat-field-metadatas-to-create.util.ts

@@ -48,6 +48,7 @@ export const fromCreateObjectInputToFlatObjectMetadataAndFlatFieldMetadatasToCre
       buildDefaultFlatFieldMetadatasForCustomObject({
         flatObjectMetadata: {
           id: objectMetadataId,
+          applicationId: createObjectInput.applicationId ?? null,
         },
         workspaceId,
       });

packages/twenty-server/src/engine/metadata-modules/flat-object-metadata/utils/recompute-view-field-identifier-after-flat-object-identifier-update.util.ts

@@ -66,6 +66,7 @@ export const recomputeViewFieldIdentifierAfterFlatObjectIdentifierUpdate = ({
         deletedAt: null,
         universalIdentifier: viewFieldId,
         aggregateOperation: null,
+        applicationId: existingFlatObjectMetadata.applicationId,
       };
 
       accumulator.flatViewFieldToCreate.push(flatViewFieldToCreate);