chore: migrate to renovatebot, add support for GitHub actions (#29045)

GitHub Actions is [transitioning from Node 16 to Node
20](https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to-node-20/).
As a result, we have several GitHub Actions that need to be updated.
Rather than update these actions manually, I decided to have Renovatebot
do it. This PR adds Renovatebot so it can automatically create PRs to
update our GitHub Actions dependencies. I also migrated the Dependabot
config to use Renovatebot so we don't have two dependency management
tools.

Example test run:
https://github.com/liamdebeasi/framework-renovate-test/pulls

Note: You can ignore the Docker update. I am using this fork for
Docker-related work as well.

As a result of this PR, Renovatebot will create several PRs on this repo
to update GitHub Actions dependencies.