Adding approval stage

[pm-trey]

what

Ability to have an approval stage tied to a SNS topic

why

For pipelines that require manual approval

references

N/A

[mergify[bot]]

Thanks @pm-trey for creating this pull request!

A maintainer will review your changes shortly. Please don't be discouraged if it takes a while.

While you wait, make sure to review our contributor guidelines.

[!TIP]

Need help or want to ask for a PR review to be expedited?

Join us on Slack in the #pr-reviews channel.