Clarify the cache sample and in particular that Infinispan does not
bootstrap with a default configuration file. Hence the custom
`infinispan.xml` configuration is enabled by default if Infinispan is
available on the classpath.
See gh-9417
This commit updates the cache auto-configuration to provide a
`CouchbaseCacheManager` if a `Bucket` has been configured.
The global customizer infrastructure allows to further tune the cache
manager if necessary.
Closes gh-5176
Previously, native cache libraries were favored over a standard JSR-107
implementation. If a user has a working setup using JCache with one
provider and switch to another provider, his setup may be broken if we
happen to provide a native support for the new provider.
We now consistently favor JSR-107 if it is present. Native support can
still be enabled via the `spring.cache.type` property.
Closes gh-3822
