Automate layer releases

[nhulston]

Still work in progress

What does this PR do?

Automates releases for Java layer, inspired by the same approach done in DataDog/datadog-lambda-extension#295 and DataDog/dd-trace-dotnet-aws-lambda-layer#6.

Motivation

https://datadoghq.atlassian.net/browse/SVLS-6086
and we haven't done a release in months.

Testing Guidelines

Todo

Additional Notes

Unlike .NET, we use the same layer regardless of architecture.

Types of changes

• Bug fix
• New feature
• Breaking change
• Misc (docs, refactoring, dependency upgrade, etc.)

Checklist

• This PR's description is comprehensive
• This PR contains breaking changes that are documented in the description
• This PR introduces new APIs or parameters that are documented and unlikely to change in the foreseeable future
• This PR impacts documentation, and it has been updated (or a ticket has been logged)
• This PR's changes are covered by the automated tests
• This PR collects user input/sensitive content into Datadog

[purple4reina]

Is it possible for us to update and use the pull_and_zip_layers.sh from the scripts/ directory? It will be nice to ensure that any local testing we do uses the same publishing methods as our releases.

[purple4reina]

I'm thinking specifically publish_layers.sh, pull_and_zip_layers.sh and sign_layers.sh.

[nhulston]

These scripts are different and tailored for GitLab, but after these changes we won't need the old scripts anymore -- we can remove them once I get automated releases working properly

[purple4reina]

It will be nice to keep the others, for publishing to sandbox.

[nhulston]

Closing because we need to migrate CI scripts/files to a private repo. See: https://groups.google.com/a/datadoghq.com/g/announce.dev/c/kH6Zcoqs-Hs/m/HKugsbHOAAAJ?utm_medium=email&utm_source=footer

New private repo: https://github.com/DataDog/datadog-lambda-java-ci/