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/twenty-orm/global-workspace-datasource/global-workspace-datasource.ts

@@ -112,7 +112,10 @@ export class GlobalWorkspaceDataSource extends DataSource {
     return new WorkspaceEntityManager(
       {
         workspaceId: context.authContext.workspace.id,
-        objectMetadataMaps: context.objectMetadataMaps,
+        flatObjectMetadataMaps: context.flatObjectMetadataMaps,
+        flatFieldMetadataMaps: context.flatFieldMetadataMaps,
+        flatIndexMaps: context.flatIndexMaps,
+        objectIdByNameSingular: context.objectIdByNameSingular,
         featureFlagsMap: context.featureFlagsMap,
         eventEmitterService: this.eventEmitterService,
       },

packages/twenty-server/src/engine/twenty-orm/global-workspace-datasource/global-workspace-orm.manager.ts

@@ -6,9 +6,10 @@ import { EntitySchema, ObjectLiteral } from 'typeorm';
 import { WorkspaceAuthContext } from 'src/engine/api/common/interfaces/workspace-auth-context.interface';
 
 import { WorkspaceManyOrAllFlatEntityMapsCacheService } from 'src/engine/metadata-modules/flat-entity/services/workspace-many-or-all-flat-entity-maps-cache.service';
+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';
 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 { ObjectMetadataMaps } from 'src/engine/metadata-modules/types/object-metadata-maps';
 import { WorkspaceFeatureFlagsMapCacheService } from 'src/engine/metadata-modules/workspace-feature-flags-map-cache/workspace-feature-flags-map-cache.service';
 import { WorkspacePermissionsCacheService } from 'src/engine/metadata-modules/workspace-permissions-cache/workspace-permissions-cache.service';
 import { EntitySchemaFactory } from 'src/engine/twenty-orm/factories/entity-schema.factory';
@@ -99,23 +100,8 @@ export class GlobalWorkspaceOrmManager {
         },
       );
 
-    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 { idByNameSingular: objectIdByNameSingular } =
+      buildObjectIdByNameMaps(flatObjectMetadataMaps);
 
     const metadataVersion =
       await this.workspaceCacheStorageService.getMetadataVersion(workspaceId);
@@ -139,12 +125,16 @@ export class GlobalWorkspaceOrmManager {
     const entitySchemas = await this.buildEntitySchemas(
       workspaceId,
       metadataVersion,
-      objectMetadataMaps,
+      flatObjectMetadataMaps,
+      flatFieldMetadataMaps,
     );
 
     return {
       authContext,
-      objectMetadataMaps,
+      flatObjectMetadataMaps,
+      flatFieldMetadataMaps,
+      flatIndexMaps,
+      objectIdByNameSingular,
       metadataVersion,
       featureFlagsMap,
       permissionsPerRoleId,
@@ -155,7 +145,8 @@ export class GlobalWorkspaceOrmManager {
   private async buildEntitySchemas(
     workspaceId: string,
     dataSourceMetadataVersion: number,
-    objectMetadataMaps: ObjectMetadataMaps,
+    flatObjectMetadataMaps: FlatEntityMaps<FlatObjectMetadata>,
+    flatFieldMetadataMaps: FlatEntityMaps<FlatFieldMetadata>,
   ) {
     const cachedEntitySchemaOptions =
       await this.workspaceCacheStorageService.getORMEntitySchema(
@@ -170,17 +161,16 @@ export class GlobalWorkspaceOrmManager {
         (option) => new EntitySchema(option),
       );
     } else {
-      const entitySchemas = await Promise.all(
-        Object.values(objectMetadataMaps.byId)
-          .filter(isDefined)
-          .map((objectMetadata) =>
-            this.entitySchemaFactory.create(
-              workspaceId,
-              objectMetadata,
-              objectMetadataMaps,
-            ),
+      const entitySchemas = Object.values(flatObjectMetadataMaps.byId)
+        .filter(isDefined)
+        .map((flatObjectMetadata) =>
+          this.entitySchemaFactory.create(
+            workspaceId,
+            flatObjectMetadata,
+            flatObjectMetadataMaps,
+            flatFieldMetadataMaps,
           ),
-      );
+        );
 
       await this.workspaceCacheStorageService.setORMEntitySchema(
         workspaceId,