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/twenty-orm/entity-manager/workspace-entity-manager.spec.ts

@@ -179,20 +179,20 @@ describe('WorkspaceEntityManager', () => {
     };
 
     const flatObjectMetadataMaps: FlatEntityMaps<FlatObjectMetadata> = {
-      byId: {
+      byUniversalIdentifier: {
         'test-entity-id': mockFlatObjectMetadata,
       },
-      idByUniversalIdentifier: {
+      universalIdentifierById: {
         'test-entity-id': 'test-entity-id',
       },
       universalIdentifiersByApplicationId: {},
     };
 
     const flatFieldMetadataMaps: FlatEntityMaps<FlatFieldMetadata> = {
-      byId: {
+      byUniversalIdentifier: {
         'field-id': mockFlatFieldMetadata,
       },
-      idByUniversalIdentifier: {
+      universalIdentifierById: {
         'field-id': 'field-id',
       },
       universalIdentifiersByApplicationId: {},
@@ -203,18 +203,18 @@ describe('WorkspaceEntityManager', () => {
       flatObjectMetadataMaps,
       flatFieldMetadataMaps,
       flatIndexMaps: {
-        byId: {},
-        idByUniversalIdentifier: {},
+        byUniversalIdentifier: {},
+        universalIdentifierById: {},
         universalIdentifiersByApplicationId: {},
       },
       flatRowLevelPermissionPredicateMaps: {
-        byId: {},
-        idByUniversalIdentifier: {},
+        byUniversalIdentifier: {},
+        universalIdentifierById: {},
         universalIdentifiersByApplicationId: {},
       },
       flatRowLevelPermissionPredicateGroupMaps: {
-        byId: {},
-        idByUniversalIdentifier: {},
+        byUniversalIdentifier: {},
+        universalIdentifierById: {},
         universalIdentifiersByApplicationId: {},
       },
       objectIdByNameSingular: {