Add `cloud.aws.account_decoding.enabled` config

[kaylareopelle]

The spec for account decoding has a config we have not implemented:

Agents MAY enable/disable decoding according to the setting: cloud.aws.account_decoding.enabled. This setting's value is a boolean, defaulting to true.

Implement this config, or close with a note about why we are choosing not to implement it.

[workato-integration]

https://new-relic.atlassian.net/browse/NR-347780