Fix flat entity maps date serialization (#16420)

Changes:
- as we store date in redis as serialized, let's make all flatEntity
dates as string. This requires changing FlatEntity types and making sure
that entity are converted to flatEntity and flatEntity to dtos

packages/twenty-server/src/engine/metadata-modules/view-group/services/view-group.service.ts

@@ -22,6 +22,7 @@ import {
   ViewGroupException,
   ViewGroupExceptionCode,
 } from 'src/engine/metadata-modules/view-group/exceptions/view-group.exception';
+import { fromFlatViewGroupToViewGroupDto } from 'src/engine/metadata-modules/view-group/utils/from-flat-view-group-to-view-group-dto.util';
 import { WorkspaceMigrationBuilderExceptionV2 } from 'src/engine/workspace-manager/workspace-migration-v2/exceptions/workspace-migration-builder-exception-v2';
 import { WorkspaceMigrationValidateBuildAndRunService } from 'src/engine/workspace-manager/workspace-migration-v2/services/workspace-migration-validate-build-and-run-service';
 
@@ -138,7 +139,7 @@ export class ViewGroupService {
     return findManyFlatEntityByIdInFlatEntityMapsOrThrow({
       flatEntityIds: flatViewGroupsToCreate.map((el) => el.id),
       flatEntityMaps: recomputedExistingFlatViewGroupMaps,
-    });
+    }).map(fromFlatViewGroupToViewGroupDto);
   }
 
   async updateOne({
@@ -192,10 +193,12 @@ export class ViewGroupService {
         },
       );
 
-    return findFlatEntityByIdInFlatEntityMapsOrThrow({
-      flatEntityId: optimisticallyUpdatedFlatViewGroup.id,
-      flatEntityMaps: recomputedExistingFlatViewGroupMaps,
-    });
+    return fromFlatViewGroupToViewGroupDto(
+      findFlatEntityByIdInFlatEntityMapsOrThrow({
+        flatEntityId: optimisticallyUpdatedFlatViewGroup.id,
+        flatEntityMaps: recomputedExistingFlatViewGroupMaps,
+      }),
+    );
   }
 
   async deleteOne({
@@ -251,10 +254,12 @@ export class ViewGroupService {
         },
       );
 
-    return findFlatEntityByIdInFlatEntityMapsOrThrow({
-      flatEntityId: optimisticallyUpdatedFlatViewGroupWithDeletedAt.id,
-      flatEntityMaps: recomputedExistingFlatViewGroupMaps,
-    });
+    return fromFlatViewGroupToViewGroupDto(
+      findFlatEntityByIdInFlatEntityMapsOrThrow({
+        flatEntityId: optimisticallyUpdatedFlatViewGroupWithDeletedAt.id,
+        flatEntityMaps: recomputedExistingFlatViewGroupMaps,
+      }),
+    );
   }
 
   async destroyOne({
@@ -300,7 +305,7 @@ export class ViewGroupService {
       );
     }
 
-    return existingViewGroupToDelete;
+    return fromFlatViewGroupToViewGroupDto(existingViewGroupToDelete);
   }
 
   async findByWorkspaceId(workspaceId: string): Promise<ViewGroupEntity[]> {