Check if data is same with previous data before appendDataWithKey()

[kaitian521]

In some cases, we often put some data for many times:

MMKV.put("key", "value1");
MMKV.put("key", "value2"); // value2 first time
MMKV.put("key", "value2"); // value2 second time
MMKV.put("key", "value2"); // value2 third time

When we put value2 at second time or third time, appendDataWithKey function call can be saved, to avoid of disk IO