[Feature] isolate metadata such as auth data from graph data

[javeme]

Feature Description (功能描述)

Required independent metadata:

1. db version
2. server info
3. auth data

[javeme]

@imbajin @zyxxoo please note~

[imbajin]

@imbajin @zyxxoo please note~

meta/auth data will be stored in PD later, currently we could try to enhance the clear-all API (or we provided a option to clear the graph data only)