Typescript: SASLOptions interface does not have support for AWS specific fields

[r115]

Describe the bug
When working with typescript, initializing the Kafka client for aws sasl mechanism throws a typing error.

To Reproduce

import { Kafka } from 'kafkajs';

const client = new Kafka({
   brokers: ['localhost:9092'],
   clientId: 'SampleClientId',
   ssl: true,
   sasl: {
     mechanism: 'aws',
     authorizationIdentity: 'awsidentity',
     accessKeyId: 'access_key',
     secretAccessKey: 'secret_key',
   }
})

REPL : https://repl.it/@r115/BrokenOptimalGoals

Expected behavior
Adding aws auth specific fields e.g accessKeyId should not throw a typing error.

Observed behavior
Adding aws mechanism auth fields e.g. accessKeyId throws an error.

 Type '{ mechanism: "aws"; authorizationIdentity: string; accessKeyId: string; secretAccessKey: string; }' is not assignable to type 'SASLOptions'.
  Object literal may only specify known properties, and 'authorizationIdentity' does not exist in type 'SASLOptions'.

Environment:

• OS: Mac OS 10.15.7
• KafkaJS version: 1.14.0
• Kafka version : 2.3.1
• NodeJS version: 12.16.3

Additional context
N/A