Feat workspace migration maintains flat object metadata maps (#13620)

# Introduction
The workspace migration runner v2 now computes the next
flatObjectMetadataMaps post current ws migration action has been run
So the following one have an up to date informations

## Still TODO
~~Remove any contextual information from workspace migration v2 and
consume the optimistic cache to retrieve them~~

## Next steps
- Create flat-object-metadata-maps testing toolbox and flat-object/field
testing toolbox
- Implement strong coverage on every created utils/transpiler and
applyWorkspaceMigrationAction method

packages/twenty-server/src/engine/metadata-modules/flat-object-metadata/utils/delete-flat-field-metadata-from-flat-object-metadatas.util.ts

@@ -1,7 +1,7 @@
 import { FlatFieldMetadata } from 'src/engine/metadata-modules/flat-field-metadata/types/flat-field-metadata.type';
 import { FlatObjectMetadata } from 'src/engine/metadata-modules/flat-object-metadata/types/flat-object-metadata.type';
 
-export const removeFlatFieldMetadataFromFlatObjectMetadatas = ({
+export const deleteFlatFieldMetadataFromFlatObjectMetadatas = ({
   flatFieldMetadata: flatFieldMetadataToRemove,
   flatObjectMetadatas,
 }: {

packages/twenty-server/src/engine/metadata-modules/flat-object-metadata/utils/from-flat-object-metadata-to-flat-object-metadata-with-flat-field-maps.util.ts

@@ -0,0 +1,24 @@
+import { FlatObjectMetadataWithFlatFieldMaps } from 'src/engine/metadata-modules/flat-object-metadata-maps/types/flat-object-metadata-with-flat-field-metadata-maps.type';
+import { addFlatFieldMetadataToFlatObjectMetadataWithFlatFieldMapsOrThrow } from 'src/engine/metadata-modules/flat-object-metadata-maps/utils/add-flat-field-metadata-to-flat-object-metadata-with-flat-field-maps-or-throw.util';
+import { FlatObjectMetadata } from 'src/engine/metadata-modules/flat-object-metadata/types/flat-object-metadata.type';
+
+export const fromFlatObjectMetadataToFlatObjectMetadataWithFlatFieldMaps = (
+  flatObjectMetadata: FlatObjectMetadata,
+): FlatObjectMetadataWithFlatFieldMaps => {
+  const emptyFlatObjectMetadataWithFlatFieldMaps: FlatObjectMetadataWithFlatFieldMaps =
+    {
+      ...flatObjectMetadata,
+      fieldIdByJoinColumnName: {},
+      fieldIdByName: {},
+      fieldsById: {},
+    };
+
+  return flatObjectMetadata.flatFieldMetadatas.reduce(
+    (flatObjectMetadataWithFlatFieldMaps, flatFieldMetadata) =>
+      addFlatFieldMetadataToFlatObjectMetadataWithFlatFieldMapsOrThrow({
+        flatFieldMetadata,
+        flatObjectMetadataWithFlatFieldMaps,
+      }),
+    emptyFlatObjectMetadataWithFlatFieldMaps,
+  );
+};

packages/twenty-server/src/engine/metadata-modules/flat-object-metadata/utils/merge-two-flat-object-metadatas.util.ts

@@ -11,7 +11,10 @@ import { ToMerge } from 'src/engine/workspace-manager/workspace-migration-v2/wor
 export const mergeTwoFlatObjectMetadatas = ({
   destFlatObjectMetadatas,
   toMergeFlatObjectMetadatas,
-}: ToMerge<FlatObjectMetadata[], 'object'>): FlatObjectMetadata[] => {
+}: ToMerge<
+  FlatObjectMetadata[],
+  'FlatObjectMetadatas'
+>): FlatObjectMetadata[] => {
   const initialObjectAccumulator = fromArrayToUniqueKeyRecord({
     array: destFlatObjectMetadatas,
     uniqueKey: 'uniqueIdentifier',