Migrate all dependency scanning to dependabot

[jcscottiii]

Currently, wpt.fyi uses dependabot (first party) and renovate (third party). This issue tracks the work to move all of it to dependabot.

There was a great discussion in issue #2948 about the pros and cons of each one.

Definition of done:

• [ ] Add reviewed deployments for dependabot PRs
• [ ] Move go and node scanning from renovate to dependabot. Switch to scanning weekly.
• [ ] Add docker scanning