[REFACTOR] remove deref impl on Cache type

[Chethan-rao]

Currently Cache is a type having inner value as MokaCache.

pub struct Cache {
    inner: MokaCache<String, Arc<dyn Cacheable>>,
}

There's a deref impl for this type which returns the inner MokaCache. We should instead have custom methods on Cache which calls the MokaCache methods instead of deref doing the job. There's already custom methods available on Cache. Invoke these method instead of calling it on the deref of Cache.