Auto-configure cache infrastructure to use a CacheResolver bean if present

[Crain-32]

This can be seen an extension of this conversation from Framework, which I originally posted thinking I was in Spring Boot's Issues (I've checked 5 times that this is Boot already while writing this)

Currently Spring Boot's Autoconfiguration will handle if you provide a CacheManager Bean, however won't handle if you provide a CacheResolver bean. Both beans should like either require CachingConfigurer, or not. Currently it's one requires it, the other doesn't.

[snicoll]

This is a fair point. The reason why this happens this way stems in framework. If you provide a CacheManager bean we will use that. For any other advanced configuration, the configurer is required. I am not sure this should be fixed here, actually, even if we already provided implementations of configurer in the past for convenience.

I'll check what our options are.

[snicoll]

Looking at the auto-configuration, and #5201 in particular, I think there's not much we can do at this point.

CacheResolver is an advanced SPI and anything we'd do to automatically wrap it could break others. Thanks for the suggestion, in any case.