fix: add async to the method using setFindOptions()

[bindon]

Description of change

• Although the return type in TypeScript is Promise<>, it is not possible to catch as shown below (not promise return)
• This is because 5 modified methods are set to sync.

// definition: Repository<IamOrganization>.exists(options?: FindManyOptions<IamOrganization> | undefined): Promise<boolean>
// expected error: Promise.reject(EntityPropertyNotFoundError)

// AS-IS(not working)
this.repository.exists({ select: 'not_exists' }).catch((error) => console.error);

// AS-IS(working)
try {
  this.repository.exists({ select: 'not_exists' });
} catch (error) {
  console.error(error);
}

// TO-BE(working)
this.repository.exists({ select: 'not_exists' }).catch((error) => console.error);
// or
try {
  await this.repository.exists({ select: 'not_exists' });
} catch (error) {
  console.error(error);
}

Pull-Request Checklist

• Code is up-to-date with the master branch
• npm run format to apply prettier formatting
• npm run test passes with this change
• This pull request links relevant issues as Fixes #0000 - N/A
• There are new or updated unit tests validating the change - N/A
• Documentation has been updated to reflect this change - N/A
• The new commits follow conventions explained in CONTRIBUTING.md