Use new gradle plugins for validation model and protocol tests

[hpmellema]

Background

• Updates the protocol test and validation model packages to use the updated gradle plugins.
• Adds a new workflow to automatically check for updates to the gradle plugin and update the plugin if the main repo is behind.
• Commits the formatter changes applied by the plugin to the validation model.

Testing

• N/A

Links

• The periodic auto-update workflow is copied from the workflow used in the examples repo: https://github.com/smithy-lang/smithy-examples/blob/main/.github/workflows/update-smithy-gradle-plugin-version.yml

---

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.