feat(database): Add trigger to set impersonation on first user (#9195)

Introduced a trigger to automatically set `canImpersonate` to true for
the first user inserted into the `core.user` table. The trigger is
removed after the first user is added to ensure this behavior only
applies to the initial user. Includes both the creation and rollback
logic for the migration.

Close #9173

packages/twenty-server/src/engine/core-modules/auth/services/sign-in-up.service.ts

@@ -324,9 +324,20 @@ export class SignInUpService {
     lastName: string;
     picture: SignInUpServiceInput['picture'];
   }) {
+    const user: Partial<User> = {
+      email,
+      firstName,
+      lastName,
+      canImpersonate: false,
+      passwordHash,
+    };
+
     if (!this.environmentService.get('IS_MULTIWORKSPACE_ENABLED')) {
       const workspacesCount = await this.workspaceRepository.count();
 
+      // if the workspace doesn't exist it means it's the first user of the workspace
+      user.canImpersonate = true;
+
       // let the creation of the first workspace
       if (workspacesCount > 0) {
         throw new AuthException(
@@ -351,23 +362,18 @@ export class SignInUpService {
 
     const workspace = await this.workspaceRepository.save(workspaceToCreate);
 
-    const imagePath = await this.uploadPicture(picture, workspace.id);
+    user.defaultAvatarUrl = await this.uploadPicture(picture, workspace.id);
 
-    const userToCreate = this.userRepository.create({
-      email: email,
-      firstName: firstName,
-      lastName: lastName,
-      defaultAvatarUrl: imagePath,
-      canImpersonate: false,
-      passwordHash,
+    const userCreated = this.userRepository.create({
+      ...user,
       defaultWorkspace: workspace,
     });
 
-    const user = await this.userRepository.save(userToCreate);
+    const newUser = await this.userRepository.save(userCreated);
 
-    await this.userWorkspaceService.create(user.id, workspace.id);
+    await this.userWorkspaceService.create(newUser.id, workspace.id);
 
-    await this.activateOnboardingForUser(user, workspace, {
+    await this.activateOnboardingForUser(newUser, workspace, {
       firstName,
       lastName,
     });
@@ -377,7 +383,7 @@ export class SignInUpService {
       value: true,
     });
 
-    return user;
+    return newUser;
   }
 
   async uploadPicture(