Refactor flat entity maps to be universal oriented (#17665)

# Introduction
In preparation of the workspace agnostic builder, we're migrating
`FlatEntityMaps` to be universal identifier oriented and based
As in the builder context there're won't be any ids at all
Please also note that the FlatEntity is a UniversalFlatEntity superset

From
```ts
import { type SyncableFlatEntity } from 'src/engine/metadata-modules/flat-entity/types/flat-entity-from.type';

export type FlatEntityMaps<T extends SyncableFlatEntity> = {
  byId: Partial<Record<string, T>>;
  idByUniversalIdentifier: Partial<Record<string, string>>;
  universalIdentifiersByApplicationId: Partial<Record<string, string[]>>;
};
```

To
```ts
export type FlatEntityMaps<
  T extends SyncableFlatEntity | UniversalSyncableFlatEntity,
> = {
  byUniversalIdentifier: Partial<Record<string, T>>;
  universalIdentifierById: Partial<Record<string, string>>;
  universalIdentifiersByApplicationId: Partial<Record<string, string[]>>; // this might make more sense to be migrated to universalIdentifiersByApplicationUniversalIdentifier but it's the main topic of this PR
};
```

## Low level maps tools
Had to refactor find | create | delete | replace | find-many | get-sub
tools ( through mutations and or throw equivalent )

packages/twenty-server/src/engine/core-modules/search/search.resolver.ts

@@ -57,7 +57,7 @@ export class SearchResolver {
       );
 
     const flatObjectMetadatas = Object.values(
-      flatObjectMetadataMaps.byId,
+      flatObjectMetadataMaps.byUniversalIdentifier,
     ).filter(isDefined);
 
     const filteredObjectMetadataItems =

packages/twenty-server/src/engine/core-modules/search/services/search.service.ts

@@ -26,6 +26,7 @@ import {
 } from 'src/engine/core-modules/search/exceptions/search.exception';
 import { type RecordsWithObjectMetadataItem } from 'src/engine/core-modules/search/types/records-with-object-metadata-item';
 import { formatSearchTerms } from 'src/engine/core-modules/search/utils/format-search-terms';
+import { findFlatEntityByIdInFlatEntityMaps } from 'src/engine/metadata-modules/flat-entity/utils/find-flat-entity-by-id-in-flat-entity-maps.util';
 import { type FlatEntityMaps } from 'src/engine/metadata-modules/flat-entity/types/flat-entity-maps.type';
 import { type FlatFieldMetadata } from 'src/engine/metadata-modules/flat-field-metadata/types/flat-field-metadata.type';
 import { type FlatObjectMetadata } from 'src/engine/metadata-modules/flat-object-metadata/types/flat-object-metadata.type';
@@ -308,10 +309,10 @@ export class SearchService {
       );
     }
 
-    const labelIdentifierField =
-      flatFieldMetadataMaps.byId[
-        flatObjectMetadata.labelIdentifierFieldMetadataId
-      ];
+    const labelIdentifierField = findFlatEntityByIdInFlatEntityMaps({
+      flatEntityId: flatObjectMetadata.labelIdentifierFieldMetadataId,
+      flatEntityMaps: flatFieldMetadataMaps,
+    });
 
     if (!isDefined(labelIdentifierField)) {
       throw new SearchException(
@@ -355,10 +356,10 @@ export class SearchService {
       return null;
     }
 
-    const imageIdentifierField =
-      flatFieldMetadataMaps.byId[
-        flatObjectMetadata.imageIdentifierFieldMetadataId
-      ];
+    const imageIdentifierField = findFlatEntityByIdInFlatEntityMaps({
+      flatEntityId: flatObjectMetadata.imageIdentifierFieldMetadataId,
+      flatEntityMaps: flatFieldMetadataMaps,
+    });
 
     if (!isDefined(imageIdentifierField)) {
       return null;