TBD: feat: add generic serializer impl

[yikakia]

To address the issue in #72 #72 (comment), a generic Marshaler implementation has been added.

Outstanding tasks:

• Test cases for Serializer
• Compatibility tests with Loadable

Items for discussion:

1. Should Marshaler be directly replaced instead of creating a new Serializer?
2. The original implementation supported both []byte and string types; is continued support necessary?
3. Are the parameters for this constructor method appropriate?
4. Design question: Should the StoreInterface itself determine whether to serialize? After CacheInterface supports generics, users would expect to directly retrieve the corresponding object T, rather than concerning themselves with how object T is converted into the format supported by each StoreInterface, or how to deserialize from the string or []byte returned by each StoreInterface back into object T.

Translated from chinese
为了解决 #72 中的问题 #72 (comment) 增加泛型的 Marshaler 实现

未完成的工作：

• Serializer 的测试用例
• 与 Loadable 的兼容性测试

待讨论项：

1. 是否应直接替换 Marshaler 而非新建一个 Serializer
2. 原来的实现中兼容了类型为 []byte 和 string 的两种情况，是否需要继续支持
3. 这个构造方法的参数是否合适
4. 设计问题：序列化与否是否应该由 StoreInterface 自己决定？CacheInterface 支持泛型后，用户期望的应该是直接能拿到对应的 obj T ，而不是 obj T 怎么转为每个 StoreInterface 支持的格式，怎么从每个 StoreInterface 返回的 string 或 []byte 反序列化回 obj T