feat(NODE-6988)!: require aws sdk for aws auth

[durran]

Description

Requires @aws-sdk/credential-providers in order to perform AWS authentication.

Summary of Changes

• Removes our implementation of AWS credential fetching.
• Updates AWS tests.

What is the motivation for this change?

NODE-6988

Release Highlight

@aws-sdk/credential-providers is now required for MONGODB-AWS authentication

Previous versions of the driver contained two implementations for AWS authentication and could run the risk of the custom driver implementation not supporting all AWS authentication features as well as not being correct when AWS makes changes. Using the official AWS SDK in all cases alleviates these issues.

npm install @aws-sdk/credential-providers

Double check the following

• Lint is passing (npm run check:lint)
• Self-review completed using the steps outlined here
• PR title follows the correct format: type(NODE-xxxx)[!]: description
  • Example: feat(NODE-1234)!: rewriting everything in coffeescript
• Changes are covered by tests
• New TODOs have a related JIRA ticket

[baileympearson]

Woohoo code deletion! Just a few small comments.

[dariakp]

@durran Can we add additional context in the release highlight to explain how the change benefits our users?

[durran]

@durran Can we add additional context in the release highlight to explain how the change benefits our users?

@dariakp Updated.