Configuration key to handle DuplicatePermalinkOutputError

[patrulea]

Is your feature request related to a problem? Please describe.

I’ve been building sites that feed on a CMS that I hand to clients so they can author their own content. Though, I’ve had them contact me with “my new content isn’t showing up online,” just to discover a Failed build log on Netlify related to some DuplicatePermalinkOutputError thrown by Eleventy.

Describe the solution you'd like

I imagine some key on the configuration file to customize this behavior so it doesn’t crash the build, but just log a warning and maybe handle a solution.

Something like strict (default; crashes the build), ignore (outputs only the first file in the queue, ignore the rest, and log the details to the console), resolve (add a numbered suffix to resolve the conflict), and/or custom (template-like syntax to set a solution when this conflict appears).

Describe alternatives you've considered

I tell them not to create duplicate blog entries with identical metadata because I knew this could happen. And I could over-engineer a solution to prevent the authors to replicate this error. But maybe Eleventy could handle this natively as well.

Additional context

Related: #562