Implemented dataloader for relation metadata (#4891)

- Implemented dataloader package on metadata graphql server
- Implemented a dataloader for relation metadata module

---------

Co-authored-by: Jérémy M <jeremy.magrin@gmail.com>

packages/twenty-server/src/engine/dataloaders/dataloader.service.ts

@@ -0,0 +1,32 @@
+import { Injectable } from '@nestjs/common';
+
+import DataLoader from 'dataloader';
+
+import { IDataloaders } from 'src/engine/dataloaders/dataloader.interface';
+import { RelationMetadataEntity } from 'src/engine/metadata-modules/relation-metadata/relation-metadata.entity';
+import { RelationMetadataService } from 'src/engine/metadata-modules/relation-metadata/relation-metadata.service';
+
+@Injectable()
+export class DataloaderService {
+  constructor(
+    private readonly relationMetadataService: RelationMetadataService,
+  ) {}
+
+  createLoaders(): IDataloaders {
+    const relationMetadataLoader = new DataLoader<
+      string,
+      RelationMetadataEntity
+    >(async (fieldMetadataIds: string[]) => {
+      const relationsMetadataCollection =
+        await this.relationMetadataService.findManyRelationMetadataByFieldMetadataIds(
+          fieldMetadataIds,
+        );
+
+      return relationsMetadataCollection;
+    });
+
+    return {
+      relationMetadataLoader,
+    };
+  }
+}