[metadata]: Analyse and define a Interface for metadata service

[PravinRanjan10]

Issue/Feature Description:

• Create a Interface and it's possible methods
• Define protobuf message file
• Use protoc to auto-generate pb file of this proto file

Why this issue to fixed / feature is needed(give scenarios or use cases):

How to reproduce, in case of a bug:

Other Notes / Environment Information: (Please give the env information, log link or any useful information for this issue)