Refine the deployment workflows until they are consistently working

[KevinMind]

Description

In this step we should refine the workflow executed by deploy-amo to determine which image tag to deploy and to trigger the actual deployment.

We can infer the image tag a number of different ways, but the most reliable would be to follow a similar path as we did for the circleCI deployment flow.

1. The event willl give us information about the CI workflow that triggered the deployment. This will include the run ID
2. From the run ID we can use the github API to query the build job and download the logs for that job
3. In the logs will be the precise image tag, version, and digest.

The rest of the workflow is already implemented in the existing workflows so all we have to do is modify where we download the logs from and how to find the image digest. Then we pass the image digest down the workflow and everything remains the same.

Example downloading gh job logs

gh --repo mozilla/addons-server run view --log --job=26437970587

Note, we do eventually want to push the image directly to GAR but this can be a second step after this one.

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