Come up with solution to prevent redeploying too often

[hellais]

Problem:

At the moment whenever something lands in master this triggers a rebuild and deployment of every configured service, including those which are not affected by any changes to the code.

For example if I make changes only to ooniauth, oonirun is also redeployed too. This should not really have any real impact and is not a big problem at the moment since we don't have too many services, however in the future this is problematic for 2 reasons:

1. A change to an unrelated service might trigger the deployment of a broken unrelated service
2. Even if 1. is mitigate, we are still building a new package and redeploying it for no reason (if our builds were reproducible it would be the exactly same package) costing us CPU cycles.

Possible solutions:

• Add filtering to the codebuild/codepipeline tasks so that a deploy is only triggered when changes affect a specific tree (similar to how you would do this with the github: https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#example-including-and-excluding-paths)
• Split up each service in their own sub-repo