Allow overriding the built-in cache handler

[cjpearson]

Describe the feature

Based on this comment

Adding a cacheHandler option to the nitro config would allow applications and modules to customize the caching behavior of nitro.

I'm thinking one approach could be to mimic the behavior of errorHandler. (But not allowing an array) Here the cache handler could be imported from #nitro-internal-virtual/cache-handler instead which would resolve to the configured handler if provided, or fallback to the default one.

https://nitro.build/config#errorhandler

Additional information

• Would you be willing to help implement this feature?

[pi0]

An (auto) import with a different name can be used for any different implementation.

Changing built-in behavior implicitly by option is not a really good idea (error handler is really different story).