Deprecate object metadata maps in favor of flat entities (#16080)

## Context
Deprecating the old objectMetadataMap type in favour of split flat
entities to match with our new caching.
In the long run, trying to achieve:
- Better performance through caching
- Consistent data access patterns across the codebase
- Reduced database queries

Now that everything is based on flat entities, which are cached, we can
finish the refactoring of workspace context cache which should already
improve performances.
Then the last step will be to consume that new cache in the new global
datasource to get rid of the many workspace datasources stored in the
server

packages/twenty-server/src/engine/api/graphql/workspace-schema.factory.ts

@@ -14,7 +14,6 @@ import {
   AuthExceptionCode,
 } from 'src/engine/core-modules/auth/auth.exception';
 import { type AuthContext } from 'src/engine/core-modules/auth/types/auth-context.type';
-import { FeatureFlagService } from 'src/engine/core-modules/feature-flag/services/feature-flag.service';
 import { DataSourceService } from 'src/engine/metadata-modules/data-source/data-source.service';
 import {
   FlatEntityMapsException,
@@ -22,11 +21,7 @@ import {
 } from 'src/engine/metadata-modules/flat-entity/exceptions/flat-entity-maps.exception';
 import { WorkspaceManyOrAllFlatEntityMapsCacheService } from 'src/engine/metadata-modules/flat-entity/services/workspace-many-or-all-flat-entity-maps-cache.service';
 import { buildObjectIdByNameMaps } from 'src/engine/metadata-modules/flat-object-metadata/utils/build-object-id-by-name-maps.util';
-import { buildObjectMetadataItemWithFieldMaps } from 'src/engine/metadata-modules/flat-object-metadata/utils/build-object-metadata-item-with-field-maps.util';
-import { type ObjectMetadataMaps } from 'src/engine/metadata-modules/types/object-metadata-maps';
 import { WorkspaceCacheStorageService } from 'src/engine/workspace-cache-storage/workspace-cache-storage.service';
-import { standardObjectMetadataDefinitions } from 'src/engine/workspace-manager/workspace-sync-metadata/standard-objects';
-import { shouldExcludeFromWorkspaceApi } from 'src/engine/workspace-manager/workspace-sync-metadata/utils/should-exclude-from-workspace-api.util';
 
 @Injectable()
 export class WorkspaceSchemaFactory {
@@ -37,7 +32,6 @@ export class WorkspaceSchemaFactory {
     private readonly workspaceResolverFactory: WorkspaceResolverFactory,
     private readonly workspaceCacheStorageService: WorkspaceCacheStorageService,
     private readonly workspaceManyOrAllFlatEntityMapsCacheService: WorkspaceManyOrAllFlatEntityMapsCacheService,
-    private readonly featureFlagService: FeatureFlagService,
   ) {}
 
   async createGraphQLSchema(authContext: AuthContext): Promise<GraphQLSchema> {
@@ -82,8 +76,12 @@ export class WorkspaceSchemaFactory {
       );
     }
 
-    const workspaceFeatureFlagsMap =
-      await this.featureFlagService.getWorkspaceFeatureFlagsMap(workspaceId);
+    if (!isDefined(flatFieldMetadataMaps)) {
+      throw new FlatEntityMapsException(
+        'Field metadata collection not found',
+        FlatEntityMapsExceptionCode.ENTITY_NOT_FOUND,
+      );
+    }
 
     let metadataVersion =
       await this.workspaceCacheStorageService.getMetadataVersion(workspaceId);
@@ -99,37 +97,7 @@ export class WorkspaceSchemaFactory {
     const { idByNameSingular } = buildObjectIdByNameMaps(
       flatObjectMetadataMaps,
     );
-    const objectMetadataMaps: ObjectMetadataMaps = {
-      byId: {},
-      idByNameSingular,
-    };
 
-    for (const [id, flatObj] of Object.entries(flatObjectMetadataMaps.byId)) {
-      if (isDefined(flatObj)) {
-        objectMetadataMaps.byId[id] = buildObjectMetadataItemWithFieldMaps(
-          flatObj,
-          flatFieldMetadataMaps,
-          flatIndexMaps,
-        );
-      }
-    }
-
-    const objectMetadataCollection = Object.values(objectMetadataMaps.byId)
-      .filter(isDefined)
-      .map((objectMetadataItem) => ({
-        ...objectMetadataItem,
-        fields: Object.values(objectMetadataItem.fieldsById),
-        indexes: objectMetadataItem.indexMetadatas,
-      }))
-      .filter((objectMetadata) => {
-        return !shouldExcludeFromWorkspaceApi(
-          objectMetadata,
-          standardObjectMetadataDefinitions,
-          workspaceFeatureFlagsMap,
-        );
-      });
-
-    // Get typeDefs from cache
     let typeDefs = await this.workspaceCacheStorageService.getGraphQLTypeDefs(
       authContext.workspace.id,
       metadataVersion,
@@ -140,12 +108,13 @@ export class WorkspaceSchemaFactory {
         metadataVersion,
       );
 
-    // If typeDefs are not cached, generate them
     if (!typeDefs || !usedScalarNames) {
       const autoGeneratedSchema =
-        await this.workspaceGraphQLSchemaGenerator.generateSchema(
-          objectMetadataCollection,
-        );
+        await this.workspaceGraphQLSchemaGenerator.generateSchema({
+          flatObjectMetadataMaps,
+          flatFieldMetadataMaps,
+          flatIndexMaps,
+        });
 
       usedScalarNames =
         this.scalarsExplorerService.getUsedScalarNames(autoGeneratedSchema);
@@ -165,7 +134,9 @@ export class WorkspaceSchemaFactory {
 
     const autoGeneratedResolvers = await this.workspaceResolverFactory.create(
       authContext,
-      objectMetadataMaps,
+      flatObjectMetadataMaps,
+      flatFieldMetadataMaps,
+      idByNameSingular,
       workspaceResolverBuilderMethodNames,
     );
     const scalarsResolvers =