How to register amazon-ssm-agent on ubuntu with different AWS SSM Patch baseline?

Hi,

I am using ubuntu 20.04 machines with AWS SSM and amazon-ssm-agent snap package to manage said machines via SSM.
In AWS Systems manager (SSM) i have default patch baseline, which is used by all new machines, and i have created a new 'test baseline' with different versions of patches.

question is - how to configure ssm-agent on the ubuntu machine to use different patch baseline rather than default one?

I am using following command to register the ubuntu machines:

```
sudo /snap/amazon-ssm-agent/current/amazon-ssm-agent -register \
-tags 'Key=PatchGroup,Value=default-group' \
-code "$CODE" \
-id "$ID" \
-region us-east-1 -y
```

thanx

Review the AWS Systems Manager patch-baseline and PatchGroup registration flow invoked by the amazon-ssm-agent -register command shown in the issue. Start with the Ubuntu 20.04 snap command and determine how association with a non-default baseline should be configured; done means documenting the required configuration and how to verify it on a test instance.

Written by the indexing model from the issue text.