Add error_handler option as Proc to Dalli::Store

[johnnyshields]

Currently Dalli::Store supports a raise_errors (true/false) config.

I'd like more fine grained error handling like Rail's Redis Store supports. Would propose to add error_handler option as a proc, which is what Redis does.

My main reason for this is related to: rack/rack-attack#577

[petergoldstein]

@johnnyshields Dalli::Store is no longer supported. It was deprecated in the 2.7.x versions and removed with 3.0.x.

You can find the MemCacheStore class here - https://github.com/rails/rails/blob/main/activesupport/lib/active_support/cache/mem_cache_store.rb

[johnnyshields]

Thanks, will close issue!