General Filter & Portrait Mode Filter - Pack & return data to front end

[XiaoSong9905]

Info

1. return data to front end follow gRPC protocol
2. It turns out that we can directly send images through HTTP requests. This function becomes trivial then.

Feature Links

https://github.com/DynamicProgrammingEECS441/PicassoXS/blob/master/src/backend/tfserver/QuickStart.md
https://github.com/DynamicProgrammingEECS441/PicassoXS/blob/master/src/backend/tfserver/quickstart.py
The above links explain how we can send data back and forth between the frontend and the backend.

User Story & Acceptance Criteria

General Filter: https://docs.google.com/document/d/1YU66XGAY_96yoz0vlgMPM-049zOeC4QVQgMvJiivYsE/edit?usp=sharing

Portrate Mode Filter : https://docs.google.com/document/d/1BMszGmVqfQa7ZOoLGFx_vB3N_HeCxCEe_6KgkWVSmRo/edit?usp=sharing

Additional Acceptance Criteria : frontend should be able to use data to get styled photo