fix: stop column transformers from modifying where

[Hanssen0]

Description of change

This change stops column transformers from modifying the original where criteria.

@Entity()
export class Job {
  @Column({
    type: "varchar",
    transformer: {
      from: (raw: string): Date => new Date(raw),
      to: (date: Date): string => date.toISOString(),
    },
  })
  submittedAt: Date;
}

// ...

const criteria = {
  submittedAt: MoreThanOrEqual(sinceTime),
};

await jobRepo.findBy(criteria);
await jobRepo.findBy(criteria);

The FindOperator within the where was changed during the first findBy, causing the second query to fail by trying to transform a transformed value.

This PR tries to fix this problem.

Pull-Request Checklist

• Code is up-to-date with the master branch
• npm run format to apply prettier formatting
• I want to keep files that I didn't touch.
• npm run test passes with this change
• They failed but were not related to this change.
• This pull request links relevant issues as Fixes #0000 N/A
• There are new or updated unit tests validating the change
• Documentation has been updated to reflect this change
• The new commits follow conventions explained in CONTRIBUTING.md