FR: Add support for Amazon Bottlerocket vulnerability source

[pna-nca]

Hi,

We are using NeuVector deployment on AWS EKS-based Kubernetes deployment.
The corresponding EKS compute instances are using AWS Bottlerocket image.
Although the Bottlerocket flavor is quite secure by design, it still contains vulnerabilities.

As far as I see AWS publishes the vulnerability data here: https://advisories.bottlerocket.aws/updateinfo.xml.gz
See this discussion for details: bottlerocket-os/bottlerocket#4063