DRAFT feat: allow setting or unsetting the boto retry configuration

[ryancausey]

DRAFT feature for #1268

[ryancausey]

@ikonst this is my first attempt at adding this feature. I wanted to check that this was in line with what we discussed in #1268 before polishing and adding tests. Please review and let me know, thanks!

[ryancausey]

The good news is this change works locally for me and confirms that botocore is handling the AWS SDK configuration discovery logic, not boto3. I was able to override the setting to be None and it automatically picked up the retry configuration values in my ~/.aws/config file.