feat(dynamodb): Use ProjectionExpression when requested_features is set by Jwrede · Pull Request #6366 · feast-dev/feast

The requested_features parameter was accepted by online_read and
online_read_async but never used -- DynamoDB always fetched all
features stored in the values map regardless. Add a
ProjectionExpression to BatchGetItem requests when requested_features
is provided, reducing data transfer, latency, and read costs.

Fixes feast-dev#6058

Signed-off-by: Jonathan Wrede <wrede.jonathan00@gmail.com>

The return dict contains both str and Dict[str, str] values, so the
return type must be Dict[str, Any] not Dict[str, str].

Signed-off-by: Jonathan Wrede <wrede.jonathan00@gmail.com>