[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() { 
    }

CheckList

Thanks for considering to this repository. Before you submit your issue, please confirm these boxes are checked.

• I have read 《[EN]Style guide for Swift repo [CN]Swift项目代码规范、规约选型》.
• 我遵守一下 Merge 规则：邀请群组中任意一人进行review，即可合并。让 reviewer 在 PR 所在页面写下review意见表示通过，即可合并。最简单写一句 LGTM 也可以。不按照本规则执行，自己 PR 自己 Merge 并引入问题，会被收回 Merge 权限。

My issue:

---

What I have done:

[0x1306a94]

LGTM