Add new basic_cas that resembles production setup

[blakehatch]

Description

This variant of basic_cas is based on a production setup combined with the convience of using basic_cas locally as an all-in-one CAS, AC, and Worker,

Type of change

• New feature (non-breaking change which adds functionality)
• This change requires a documentation update

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This change is 

[allada]

Reviewed all commit messages.
Reviewable status: 0 of 1 LGTMs obtained, and 1 discussions need to be resolved

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nativelink-config/examples/basic_cas_recommended.json line 39 at r1 (raw file):

      }
    },
    "CAS_FAST_SLOW_STORE": {

nit: I don't think this will work. If used as a worker store, it needs to have the fast store be a filesystem and the slow store can be whatever.

What you actually want is to split this into a few different stores and use different ones in different places.

The CAS should use fast_slow { fast -> size_partitioning { lower -> memory, upper -> noop }, slow -> filesystem }

The worker should use: fast_slow { fast -> filesystem, slow -> noop } (but put comment that noop should be replaced with a remote storage store (S3, GRPC, Redis, exc...).

The filesystem stores both are referencing should be the same store.