Introducing view field group syncable entity (#17867)

## Context
Introduces a new viewFieldGroup entity that allows grouping view fields
into sections (e.g. "General", "Additional", "Other") within a view.

The page layout fields widget needs a way to organize fields into
sections. Today, views have no concept of field grouping. This PR
introduces the viewFieldGroup entity which sits between a view and its
viewFields, enabling section-based organization.

<img width="401" height="724" alt="Layout - V2 (customize visibility)"
src="https://github.com/user-attachments/assets/6376e2ab-44db-42bf-9d2c-758f56f6b548"
/>

---------

Co-authored-by: Charles Bochet <charles@twenty.com>

packages/twenty-server/src/engine/workspace-manager/twenty-standard-application/constants/twenty-standard-all-metadata-name.constant.ts

@@ -5,6 +5,7 @@ export const TWENTY_STANDARD_ALL_METADATA_NAME = [
   'objectMetadata',
   'fieldMetadata',
   'viewField',
+  'viewFieldGroup',
   'viewFilter',
   'viewGroup',
   'view',

packages/twenty-server/src/engine/workspace-manager/twenty-standard-application/utils/twenty-standard-application-all-flat-entity-maps.constant.ts

@@ -97,6 +97,8 @@ export const computeTwentyStandardApplicationAllFlatEntityMaps = ({
 
   const flatViewFilterGroupMaps = createEmptyFlatEntityMaps();
 
+  const flatViewFieldGroupMaps = createEmptyFlatEntityMaps();
+
   const flatViewFilterMaps = buildStandardFlatViewFilterMetadataMaps({
     dependencyFlatEntityMaps: {
       flatFieldMetadataMaps,
@@ -114,6 +116,7 @@ export const computeTwentyStandardApplicationAllFlatEntityMaps = ({
       flatObjectMetadataMaps,
       flatFieldMetadataMaps,
       flatViewMaps,
+      flatViewFieldGroupMaps,
     },
     now,
     standardObjectMetadataRelatedEntityIds,
@@ -188,6 +191,7 @@ export const computeTwentyStandardApplicationAllFlatEntityMaps = ({
 
   const allFlatEntityMaps: TwentyStandardAllFlatEntityMaps = {
     flatViewFieldMaps,
+    flatViewFieldGroupMaps,
     flatViewFilterMaps,
     flatViewGroupMaps,
     flatViewMaps,

packages/twenty-server/src/engine/workspace-manager/twenty-standard-application/utils/view-field/create-standard-view-field-flat-metadata.util.ts

@@ -88,6 +88,8 @@ export const createStandardViewFieldFlatMetadata = <
     fieldMetadataId:
       standardObjectMetadataRelatedEntityIds[objectName].fields[fieldName].id,
     fieldMetadataUniversalIdentifier: fieldDefinition.universalIdentifier,
+    viewFieldGroupId: null,
+    viewFieldGroupUniversalIdentifier: null,
     position,
     isVisible,
     size,

packages/twenty-server/src/engine/workspace-manager/twenty-standard-application/utils/view/create-standard-view-flat-metadata.util.ts

@@ -142,6 +142,8 @@ export const createStandardViewFlatMetadata = <
     createdByUserWorkspaceId: null,
     viewFieldIds: [],
     viewFieldUniversalIdentifiers: [],
+    viewFieldGroupIds: [],
+    viewFieldGroupUniversalIdentifiers: [],
     viewFilterIds: [],
     viewFilterUniversalIdentifiers: [],
     viewGroupIds: [],