Instantiating `Mail` class with personalizations overrides the substitution wrapper of the provided personalizations

[abetoots]

An example pseudo code:

  import { classes as sgClasses } from "@sendgrid/helpers";

  const Mail = sgClasses.Mail;
  const Personalization = sgClasses.Personalization;

  const samplePersonalization =  new Personalization();
  samplePersonalization.setTo("sample@email.com");
  samplePersonalization.addSubstitution("name", "Sample");
  samplePersonalization.setSubstitutionWrappers(["%%", "%%"]);

  //sample data
  const data = {
    ...,
    personalizations: [samplePersonalization]
  };

  const mail = new Mail(data);

Expected mail structure:

//mail.toJSON() result
{
 personalizations: [
       {
        substitutions: {
          '%%name%%': 'Sample'
          }
       }
  ]
}

Actual:

//mail.toJSON() result
{
 personalizations: [
       {
        substitutions: {
          '{{%%name%%}}': 'Sample'
          }
       }
  ]
}

As you can see, it is adding the default wrappers. I found the issue is because it does not pass this line because the data is being deep cloned here