Morph Relations : deleteOneField (#13349)

This PR adapts teh deleteOneField to make sure morph relations can be
deleted, either
- from a relation type, 
- or from a morph relation type (which is the most obvious case).

This PR covers 
- the deletion of fieldMetadata 
- and the migrationof workspace schemas, by using the already existing
definition of relation migrations

This PR implements a new test suite: "Delete Object metadata with morph
relation" and completes the other test suites for FieldMetadata and
ObjectMetadata creation/deletion.

Last, we added a nitpick from @paul I forgot on a previous PR on
process-nested-realtion-v2

Fixes https://github.com/twentyhq/core-team-issues/issues/1197

packages/twenty-server/src/engine/api/graphql/graphql-query-runner/helpers/process-nested-relations-v2.helper.ts

@@ -4,7 +4,6 @@ import { FieldMetadataType } from 'twenty-shared/types';
 import { FindOptionsRelations, ObjectLiteral } from 'typeorm';
 
 import { ObjectRecord } from 'src/engine/api/graphql/workspace-query-builder/interfaces/object-record.interface';
-import { FieldMetadataRelationSettings } from 'src/engine/metadata-modules/field-metadata/interfaces/field-metadata-settings.interface';
 import { RelationType } from 'src/engine/metadata-modules/field-metadata/interfaces/relation-type.interface';
 
 import {
@@ -175,7 +174,7 @@ export class ProcessNestedRelationsV2Helper {
         targetRelation,
         FieldMetadataType.MORPH_RELATION,
       )
-        ? `${(targetRelation?.settings as FieldMetadataRelationSettings)?.joinColumnName}`
+        ? `${targetRelation.settings?.joinColumnName}`
         : `${targetRelationName}Id`;
 
     const { relationResults, relationAggregatedFieldsResult } =