Refactor flat entity maps to be universal oriented (#17665)

# Introduction
In preparation of the workspace agnostic builder, we're migrating
`FlatEntityMaps` to be universal identifier oriented and based
As in the builder context there're won't be any ids at all
Please also note that the FlatEntity is a UniversalFlatEntity superset

From
```ts
import { type SyncableFlatEntity } from 'src/engine/metadata-modules/flat-entity/types/flat-entity-from.type';

export type FlatEntityMaps<T extends SyncableFlatEntity> = {
  byId: Partial<Record<string, T>>;
  idByUniversalIdentifier: Partial<Record<string, string>>;
  universalIdentifiersByApplicationId: Partial<Record<string, string[]>>;
};
```

To
```ts
export type FlatEntityMaps<
  T extends SyncableFlatEntity | UniversalSyncableFlatEntity,
> = {
  byUniversalIdentifier: Partial<Record<string, T>>;
  universalIdentifierById: Partial<Record<string, string>>;
  universalIdentifiersByApplicationId: Partial<Record<string, string[]>>; // this might make more sense to be migrated to universalIdentifiersByApplicationUniversalIdentifier but it's the main topic of this PR
};
```

## Low level maps tools
Had to refactor find | create | delete | replace | find-many | get-sub
tools ( through mutations and or throw equivalent )

packages/twenty-server/src/engine/metadata-modules/flat-view-group/utils/compute-flat-view-groups-on-view-create.util.ts

@@ -7,6 +7,7 @@ import {
   FlatEntityMapsExceptionCode,
 } from 'src/engine/metadata-modules/flat-entity/exceptions/flat-entity-maps.exception';
 import { type AllFlatEntityMaps } from 'src/engine/metadata-modules/flat-entity/types/all-flat-entity-maps.type';
+import { findFlatEntityByIdInFlatEntityMaps } from 'src/engine/metadata-modules/flat-entity/utils/find-flat-entity-by-id-in-flat-entity-maps.util';
 import { type FlatViewGroup } from 'src/engine/metadata-modules/flat-view-group/types/flat-view-group.type';
 
 type ComputeFlatViewGroupsOnViewCreateArgs = {
@@ -19,8 +20,10 @@ export const computeFlatViewGroupsOnViewCreate = ({
   mainGroupByFieldMetadataId,
   flatFieldMetadataMaps,
 }: ComputeFlatViewGroupsOnViewCreateArgs): FlatViewGroup[] => {
-  const mainGroupByFieldMetadata =
-    flatFieldMetadataMaps.byId[mainGroupByFieldMetadataId];
+  const mainGroupByFieldMetadata = findFlatEntityByIdInFlatEntityMaps({
+    flatEntityId: mainGroupByFieldMetadataId,
+    flatEntityMaps: flatFieldMetadataMaps,
+  });
 
   if (!isDefined(mainGroupByFieldMetadata)) {
     throw new FlatEntityMapsException(

packages/twenty-server/src/engine/metadata-modules/flat-view-group/utils/from-delete-view-group-input-to-flat-view-group-or-throw.util.ts

@@ -5,6 +5,7 @@ import {
 } from 'twenty-shared/utils';
 
 import { type FlatViewGroupMaps } from 'src/engine/metadata-modules/flat-view-group/types/flat-view-group-maps.type';
+import { findFlatEntityByIdInFlatEntityMaps } from 'src/engine/metadata-modules/flat-entity/utils/find-flat-entity-by-id-in-flat-entity-maps.util';
 import { type FlatViewGroup } from 'src/engine/metadata-modules/flat-view-group/types/flat-view-group.type';
 import { type DeleteViewGroupInput } from 'src/engine/metadata-modules/view-group/dtos/inputs/delete-view-group.input';
 import {
@@ -24,7 +25,10 @@ export const fromDeleteViewGroupInputToFlatViewGroupOrThrow = ({
     ['id'],
   );
 
-  const existingFlatViewGroupToDelete = flatViewGroupMaps.byId[viewGroupId];
+  const existingFlatViewGroupToDelete = findFlatEntityByIdInFlatEntityMaps({
+    flatEntityId: viewGroupId,
+    flatEntityMaps: flatViewGroupMaps,
+  });
 
   if (!isDefined(existingFlatViewGroupToDelete)) {
     throw new ViewGroupException(

packages/twenty-server/src/engine/metadata-modules/flat-view-group/utils/from-destroy-view-group-input-to-flat-view-group-or-throw.util.ts

@@ -5,6 +5,7 @@ import {
 } from 'twenty-shared/utils';
 
 import { type FlatViewGroupMaps } from 'src/engine/metadata-modules/flat-view-group/types/flat-view-group-maps.type';
+import { findFlatEntityByIdInFlatEntityMaps } from 'src/engine/metadata-modules/flat-entity/utils/find-flat-entity-by-id-in-flat-entity-maps.util';
 import { type FlatViewGroup } from 'src/engine/metadata-modules/flat-view-group/types/flat-view-group.type';
 import { type DestroyViewGroupInput } from 'src/engine/metadata-modules/view-group/dtos/inputs/destroy-view-group.input';
 import {
@@ -24,7 +25,10 @@ export const fromDestroyViewGroupInputToFlatViewGroupOrThrow = ({
     ['id'],
   );
 
-  const existingFlatViewGroupToDestroy = flatViewGroupMaps.byId[viewGroupId];
+  const existingFlatViewGroupToDestroy = findFlatEntityByIdInFlatEntityMaps({
+    flatEntityId: viewGroupId,
+    flatEntityMaps: flatViewGroupMaps,
+  });
 
   if (!isDefined(existingFlatViewGroupToDestroy)) {
     throw new ViewGroupException(

packages/twenty-server/src/engine/metadata-modules/flat-view-group/utils/from-update-view-group-input-to-flat-view-group-to-update-or-throw.util.ts

@@ -7,6 +7,7 @@ import {
 
 import { type FlatEntityMaps } from 'src/engine/metadata-modules/flat-entity/types/flat-entity-maps.type';
 import { FLAT_VIEW_GROUP_EDITABLE_PROPERTIES } from 'src/engine/metadata-modules/flat-view-group/constants/flat-view-group-editable-properties.constant';
+import { findFlatEntityByIdInFlatEntityMaps } from 'src/engine/metadata-modules/flat-entity/utils/find-flat-entity-by-id-in-flat-entity-maps.util';
 import { type FlatViewGroup } from 'src/engine/metadata-modules/flat-view-group/types/flat-view-group.type';
 import { type UpdateViewGroupInput } from 'src/engine/metadata-modules/view-group/dtos/inputs/update-view-group.input';
 import {
@@ -28,8 +29,10 @@ export const fromUpdateViewGroupInputToFlatViewGroupToUpdateOrThrow = ({
       ['id'],
     );
 
-  const existingFlatViewGroupToUpdate =
-    flatViewGroupMaps.byId[viewGroupToUpdateId];
+  const existingFlatViewGroupToUpdate = findFlatEntityByIdInFlatEntityMaps({
+    flatEntityId: viewGroupToUpdateId,
+    flatEntityMaps: flatViewGroupMaps,
+  });
 
   if (!isDefined(existingFlatViewGroupToUpdate)) {
     throw new ViewGroupException(