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-field-metadata/utils/merge-two-flat-field-metadatas.util.ts

@@ -10,7 +10,7 @@ import { ToMerge } from 'src/engine/workspace-manager/workspace-migration-v2/wor
 export const mergeTwoFlatFieldMetadatas = ({
   destFlatFieldMetadatas,
   toMergeFlatFieldMetadatas,
-}: ToMerge<FlatFieldMetadata[], 'field'>): FlatFieldMetadata[] => {
+}: ToMerge<FlatFieldMetadata[], 'FlatFieldMetadatas'>): FlatFieldMetadata[] => {
   const initialRecordAccumulator = fromArrayToUniqueKeyRecord({
     array: destFlatFieldMetadatas,
     uniqueKey: 'uniqueIdentifier',