[add][MemoryCache] add `LinkedMap` , `LinkedMapNode` Class and Linked…

[birdmichael]

add class LinkedMapNode add class LinkedMap import func

    func insert(atHead node: LinkedMapNode) {
    }.
    func bring(toHead node: LinkedMapNode) { 
    }
    func remove(_ node: LinkedMapNode) {
    }
    func removeTail() -> LinkedMapNode? {
    }
    func removeAll() { 
    }

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My issue:

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What I have done:

[0x1306a94]

LGTM