SLS-1543: Automatically open PR to documentation when deploying ruby lambda layer

[IvanTopolcic]

What does this PR do?

This PR automatically adds a step at the end of deploying layers that creates a PR against the documentation with the updated version variable.

This PR clones the documentation repo to $DATADOG_ROOT/documentation if it doesn't exist, creates a new branch, makes the changes to bump the version, opens a tab to create a PR. If the documentation repo is not clean (there are local changes), then the script will fail and ask the user to continue and manually create the PR.

Motivation

Reduce friction for deploying new lambda layers.

Testing Guidelines

Changes were tested locally via the deploy sandbox lambda script.

Additional Notes

Types of Changes

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

Check all that apply

• [x] 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
• [ ] This PR passes the integration tests (ask a Datadog member to run the tests)