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/metadata-modules/flat-entity/utils/__tests__/__snapshots__/get-metadata-related-metadata-names.util.spec.ts.snap

@@ -1,4 +1,4 @@
-// Jest Snapshot v1, https://goo.gl/fbAQLP
+// Jest Snapshot v1, https://jestjs.io/docs/snapshot-testing
 
 exports[`getMetadataRelatedMetadataNames should return related metadata names for agent 1`] = `[]`;
 
@@ -108,6 +108,7 @@ exports[`getMetadataRelatedMetadataNames should return related metadata names fo
   "viewFilter",
   "viewFilterGroup",
   "viewGroup",
+  "viewFieldGroup",
 ]
 `;
 
@@ -115,6 +116,14 @@ exports[`getMetadataRelatedMetadataNames should return related metadata names fo
 [
   "fieldMetadata",
   "view",
+  "viewFieldGroup",
+]
+`;
+
+exports[`getMetadataRelatedMetadataNames should return related metadata names for viewFieldGroup 1`] = `
+[
+  "view",
+  "viewField",
 ]
 `;
 

packages/twenty-server/src/engine/metadata-modules/flat-entity/utils/__tests__/__snapshots__/sort-metadata-names-children-first.util.spec.ts.snap

@@ -4,10 +4,10 @@ exports[`sortMetadataNamesChildrenFirst should return metadata names sorted with
 [
   "rowLevelPermissionPredicate",
   "navigationMenuItem",
+  "viewField",
   "viewFilter",
   "commandMenuItem",
   "pageLayoutWidget",
-  "viewField",
   "index",
   "pageLayout",
   "roleTarget",
@@ -18,9 +18,10 @@ exports[`sortMetadataNamesChildrenFirst should return metadata names sorted with
   "logicFunction",
   "pageLayoutTab",
   "skill",
-  "view",
+  "viewFieldGroup",
   "viewFilterGroup",
   "webhook",
+  "view",
   "fieldMetadata",
   "role",
   "objectMetadata",