Make retention period configurable

[dslove]

The current retention period is fixed to 4000 days. We don't need it to be that long. This is a huge concern for us to adopt FeatureStore from cost perspective.
Suggest to make this retention option configurable, e.g. we can set how many days we want to keep the features, or how many versions we want to keep. You know, typical versioning settings.
Having such settings through lifecycle mgmt policies could be a good idea I think.