Improve object metadata maps size (#8635)

## Context
The object metadata map is becoming quite large and its structure could
be simplified.
We are removing byNameSingular/byNamePlural keys, the former can be
retrieved through a new helper and the latter is not used in the code
base currently.

packages/twenty-server/src/engine/metadata-modules/utils/__tests__/get-object-metadata-map-item-by-name-singular.util.spec.ts

@@ -0,0 +1,42 @@
+import { ObjectMetadataItemWithFieldMaps } from 'src/engine/metadata-modules/types/object-metadata-item-with-field-maps';
+import { ObjectMetadataMaps } from 'src/engine/metadata-modules/types/object-metadata-maps';
+import { getObjectMetadataMapItemByNameSingular } from 'src/engine/metadata-modules/utils/get-object-metadata-map-item-by-name-singular.util';
+
+describe('getObjectMetadataMapItemByNameSingular', () => {
+  it('should return the correct metadata item when given a valid singular name', () => {
+    const mockMetadataItem = {
+      id: 'test-id',
+      nameSingular: 'company',
+    } as ObjectMetadataItemWithFieldMaps;
+
+    const mockObjectMetadataMaps: ObjectMetadataMaps = {
+      byId: {
+        'test-id': mockMetadataItem,
+      },
+      idByNameSingular: {
+        company: 'test-id',
+      },
+    };
+
+    const result = getObjectMetadataMapItemByNameSingular(
+      mockObjectMetadataMaps,
+      'company',
+    );
+
+    expect(result).toBe(mockMetadataItem);
+  });
+
+  it('should return undefined when the singular name does not exist', () => {
+    const mockObjectMetadataMaps: ObjectMetadataMaps = {
+      byId: {},
+      idByNameSingular: {},
+    };
+
+    const result = getObjectMetadataMapItemByNameSingular(
+      mockObjectMetadataMaps,
+      'nonexistent',
+    );
+
+    expect(result).toBeUndefined();
+  });
+});