refactor: loose query key bound for in-memory cache

[MrCroxx]

What's changed and what's your intention?

Please explain IN DETAIL what the changes are in this PR and why they are needed. :D

As title.

e.g.

pub fn get(&self, key: &K) -> Option<CacheEntry<K, V, L, S>>;

will be replaced with

unsafe fn get<Q>(&mut self, hash: u64, key: &Q) -> Option<NonNull<H>>
    where
        K: Borrow<Q>,
        Q: Hash + Eq + ?Sized;

to loose query key bound like:

let entry = cache.insert("hello".to_string(), "world".to_string(), 1);
let e = cache.get(&"hello".to_string()).unwrap();

can be rewritten with

let entry = cache.insert("hello".to_string(), "world".to_string(), 1);
let e = cache.get("hello").unwrap();

Checklist

• I have written the necessary rustdoc comments
• I have added the necessary unit tests and integration tests
• I have passed make all (or make fast instead if the old tests are not modified) in my local environment.

Related issues or PRs (optional)