Following other PRs about the integration of the Cache component into the FrameworkBundle, this PR proposes the possibility to define and overide adapters from the semantic configuration.

There are three main reasons why I think we should be able to configure adapters from theconfig_*.yml files:

• to be consistent with cache pools
• because it's very useful to be able to override local/shared adapters dependeing on the environment
• because it's easier to understand the Cache components concepts in simple YAML configuration than with services (currently, to override adapters, we need to define services).

Here is an example of how we could configure every shared cache of the application to use redis instead of the filesystem with this proposal:

framework:cache:adapters:shared:parent:cache.adapter.redisprovider:app.redis_connection

By default, the FrameworkBundle defines some useful adapters and pools. Using this proposal configuration, we can represent these adapters and pools like these:

framework:#...cache:adapters:apcu:parent:~default_lifetime:~provider:~doctrine:parent:~default_lifetime:~provider:~filesystem:parent:~default_lifetime:~provider:~psr6:parent:~default_lifetime:~provider:~redis:parent:~default_lifetime:~provider:~local:parent:cache.adapter.filesystemdefault_lifetime:~provider:~shared:parent:cache.adapter.filesystemdefault_lifetime:~provider:~pools:validator:adapter:cache.adapter.localpublic:falsedefault_lifetime:~provider:~namespace:~clearer:cache.default_pools_clearerserializer:adapter:cache.adapter.localpublic:falsedefault_lifetime:~provider:~namespace:~clearer:cache.default_pools_clearerapp:adapter:cache.adapter.sharedpublic:falsedefault_lifetime:~provider:~namespace:~clearer:cache.default_pools_clearer

And every adapter could be overriden by using the keyparent or by using the same name as the parent adapter (if you redefine theredis adapter to use a different provider, it will override the parent definition).

This PR also removes thelocal andshared pool for a singleapp pool. This is done to avoid confusion for users between the local/shared adapters and the local/shared pools and because app cache will almost always be shared.