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-page-layout-widget/utils/from-destroy-page-layout-widget-input-to-flat-page-layout-widget-or-throw.util.ts

@@ -5,6 +5,7 @@ import {
 } from 'twenty-shared/utils';
 
 import { type FlatPageLayoutWidgetMaps } from 'src/engine/metadata-modules/flat-page-layout-widget/types/flat-page-layout-widget-maps.type';
+import { findFlatEntityByIdInFlatEntityMaps } from 'src/engine/metadata-modules/flat-entity/utils/find-flat-entity-by-id-in-flat-entity-maps.util';
 import { type FlatPageLayoutWidget } from 'src/engine/metadata-modules/flat-page-layout-widget/types/flat-page-layout-widget.type';
 import { type DestroyPageLayoutWidgetInput } from 'src/engine/metadata-modules/page-layout-widget/dtos/inputs/destroy-page-layout-widget.input';
 import {
@@ -25,7 +26,10 @@ export const fromDestroyPageLayoutWidgetInputToFlatPageLayoutWidgetOrThrow = ({
   );
 
   const existingFlatPageLayoutWidgetToDestroy =
-    flatPageLayoutWidgetMaps.byId[pageLayoutWidgetId];
+    findFlatEntityByIdInFlatEntityMaps({
+      flatEntityId: pageLayoutWidgetId,
+      flatEntityMaps: flatPageLayoutWidgetMaps,
+    });
 
   if (!isDefined(existingFlatPageLayoutWidgetToDestroy)) {
     throw new PageLayoutWidgetException(

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

@@ -5,6 +5,7 @@ import {
 } from 'twenty-shared/utils';
 
 import { FLAT_PAGE_LAYOUT_WIDGET_EDITABLE_PROPERTIES } from 'src/engine/metadata-modules/flat-page-layout-widget/constants/flat-page-layout-widget-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 FlatPageLayoutWidgetMaps } from 'src/engine/metadata-modules/flat-page-layout-widget/types/flat-page-layout-widget-maps.type';
 import { type FlatPageLayoutWidget } from 'src/engine/metadata-modules/flat-page-layout-widget/types/flat-page-layout-widget.type';
 import { type UpdatePageLayoutWidgetInput } from 'src/engine/metadata-modules/page-layout-widget/dtos/inputs/update-page-layout-widget.input';
@@ -34,7 +35,10 @@ export const fromUpdatePageLayoutWidgetInputToFlatPageLayoutWidgetToUpdateOrThro
       ]);
 
     const existingFlatPageLayoutWidgetToUpdate =
-      flatPageLayoutWidgetMaps.byId[pageLayoutWidgetToUpdateId];
+      findFlatEntityByIdInFlatEntityMaps({
+        flatEntityId: pageLayoutWidgetToUpdateId,
+        flatEntityMaps: flatPageLayoutWidgetMaps,
+      });
 
     if (!isDefined(existingFlatPageLayoutWidgetToUpdate)) {
       throw new PageLayoutWidgetException(