Object metadata API create one using workspace migration v2 (#13420)

# Introduction
In this PR we create basic transpilation methods and utils to handle
input to flat, entity to flat, object maps to flat. In order to
transpile everything into a common validation that will be implemented
in another PR

## FieldMetadataEntity typing
Added `never | null` to fields that should never be in order to ease
general abstracted method to pass null, as anw it's what is in the
database

## Todo
- ~~Create a feature flag~~
- Integration test for object creation through metadata api + pg col
introspection and snapshoting

packages/twenty-server/src/engine/metadata-modules/flat-field-metadata/__mocks__/get-flat-field-metadata.mock.ts

@@ -0,0 +1,56 @@
+import { faker } from '@faker-js/faker';
+import { FieldMetadataType } from 'twenty-shared/types';
+
+import { FlatFieldMetadata } from 'src/engine/metadata-modules/flat-field-metadata/types/flat-field-metadata.type';
+
+type FlatFieldMetadataOverrides<
+  T extends FieldMetadataType = FieldMetadataType,
+> = Required<
+  Pick<FlatFieldMetadata<T>, 'uniqueIdentifier' | 'objectMetadataId' | 'type'>
+> &
+  Partial<FlatFieldMetadata<T>>;
+
+export const getFlatFieldMetadataMock = <T extends FieldMetadataType>(
+  overrides: FlatFieldMetadataOverrides<T>,
+): FlatFieldMetadata => {
+  const createdAt = faker.date.anytime();
+
+  return {
+    defaultValue: null,
+    options: null,
+    settings: null,
+    createdAt,
+    description: 'default flat field metadata description',
+    icon: 'icon',
+    id: faker.string.uuid(),
+    isActive: true,
+    isCustom: true,
+    name: 'flatFieldMetadataName',
+    label: 'flat field metadata label',
+    isNullable: true,
+    isUnique: false,
+    isLabelSyncedWithName: false,
+    isSystem: false,
+    standardId: null,
+    standardOverrides: null,
+    updatedAt: createdAt,
+    workspaceId: faker.string.uuid(),
+    flatRelationTargetFieldMetadata: null,
+    relationTargetFieldMetadataId: null,
+    flatRelationTargetObjectMetadata: null,
+    relationTargetObjectMetadataId: null,
+    ...overrides,
+  };
+};
+
+export const getStandardFlatFieldMetadataMock = (
+  overrides: Omit<FlatFieldMetadataOverrides, 'isCustom' | 'isSystem'>,
+) => {
+  return getFlatFieldMetadataMock({
+    standardId: faker.string.uuid(),
+    standardOverrides: {},
+    isCustom: false,
+    isSystem: true,
+    ...overrides,
+  });
+};