Hey guys :),
According to the initial discussion that my colleague created.
I want to elaborate more about the write features API and share the proto file for initial feedback.

We think that the API should basically push feature rows for specific feature tables and projects to the online store in a similar way the ingestion logic works (RedisSinkRelation.scala).

The suggested change to the serving proto file is as follows:

Details explanation:
The PushOnlineFeatureRequest contains a definition of the feature table and the project.
And a key-value map containing the values of each row.

**We assume that the feature table and the project (if empty we use default) already exist and validate it.

The PushOnlineFeatureResponse contains a list of RowStatus that represent the pushing status of each row.

I would love to have your feedback so we can move forward and prepare a pull request soon.

Thanks!