Error handling for SesTemplateController

[fayez-nazzal]

Manually creating promises for AWS SDK is not a good practice, and It does not throw all errors

Here is the recommended way for using promises ( And handling errors, too ), by the AWS SDK docs:
Using JS Promises with AWS SDK

Here is an example updating the createTemplate function:

From:

    await new Promise((resolve, reject) => {
      //do async AWS createTemplate
      ses.createTemplate(params, function (err, data) {
        if (err) {
          reject(err);
        } else {
          resolve(data);
        }
      });
    }).then(response.send(200, 'Created')).catch(err => {
      response.status(500);
      response.send(err);
    });

To:

    await new Promise((resolve, reject) => {
       try {
          ses.createTemplate(params).promise();
          response.status(200).send("Created");
        } catch (error) {
          response.status(500).send(error.message ?? "Error creating template");
       }
    });

===> This is the recommended way, and it is required for Unit testing of error handling, issue #4

[fayez-nazzal]

@hammady