Enhancement: Config settings with dependencies should have logical checks in place

[osteensco]

PROBLEM:
Currently, it's possible to do something like the following

        config := echovault.DefaultConfig()
        config.EvictionPolicy = constants.AllKeysLRU
	Server, err := echovault.NewEchoVault(
		echovault.WithConfig(config),
	)

Because default setting for MaxMemory is 0, this causes an error when trying to interact with the server. This may not be entirely clear to a new user.

PROPOSED SOLUTION:
We should either put in logical checks when passing in configs on instantiating a server, or create separate default values for settings that are naturally coupled like MaxMemory and EvictionPolicy.

[kelvinmwinuka]

I like your proposed solution. I think we should have multiple sets of defaults and also create a validation function to solve this.