feat: manually implement joinColumn (#6022)

This PR introduce a new decorator named `@WorkspaceJoinColumn`, the goal
of this one is to manually declare the join columns inside the workspace
entities, so we don't have to rely on `ObjectRecord` type.

This decorator can be used that way:

```typescript
  @WorkspaceRelation({
    standardId: ACTIVITY_TARGET_STANDARD_FIELD_IDS.company,
    type: RelationMetadataType.MANY_TO_ONE,
    label: 'Company',
    description: 'ActivityTarget company',
    icon: 'IconBuildingSkyscraper',
    inverseSideTarget: () => CompanyWorkspaceEntity,
    inverseSideFieldKey: 'activityTargets',
  })
  @WorkspaceIsNullable()
  company: Relation<CompanyWorkspaceEntity> | null;

  // The argument is the name of the relation above
  @WorkspaceJoinColumn('company')
  companyId: string | null;
```

packages/twenty-server/src/engine/core-modules/user/services/user.service.ts

@@ -12,7 +12,6 @@ import { TypeORMService } from 'src/database/typeorm/typeorm.service';
 import { DataSourceEntity } from 'src/engine/metadata-modules/data-source/data-source.entity';
 import { WorkspaceMemberWorkspaceEntity } from 'src/modules/workspace-member/standard-objects/workspace-member.workspace-entity';
 import { ObjectRecordDeleteEvent } from 'src/engine/integrations/event-emitter/types/object-record-delete.event';
-import { ObjectRecord } from 'src/engine/workspace-manager/workspace-sync-metadata/types/object-record';
 import { WorkspaceService } from 'src/engine/core-modules/workspace/services/workspace.service';
 
 export class UserService extends TypeOrmQueryService<User> {
@@ -113,8 +112,7 @@ export class UserService extends TypeOrmQueryService<User> {
       `SELECT * FROM ${dataSourceMetadata.schema}."workspaceMember"`,
     );
     const workspaceMember = workspaceMembers.filter(
-      (member: ObjectRecord<WorkspaceMemberWorkspaceEntity>) =>
-        member.userId === userId,
+      (member: WorkspaceMemberWorkspaceEntity) => member.userId === userId,
     )?.[0];
 
     assert(workspaceMember, 'WorkspaceMember not found');