Handle Empty Dataframe write to feature store

Problem Statement:
---------------------
For now, if you do provide the empty dataframe to the write to the online store, the feast does not throws exception nor it rejects the empty dataframe.

its not failing not only for remote store but for any. I think it's good to identify the empty data at the higher level than at the store class level.

_Originally posted by @jyejare in https://github.com/feast-dev/feast/pull/5422#discussion_r2132072176_

Example:
----------
```
event_df = pd.DataFrame(
{
"driver_id": [1000, 1001],
"conv_rate": [],
"acc_rate": [],
"avg_daily_trips": [],
"event_timestamp": [],
"created": [],
}
)
# OR event a complete empty Dataframe like pd.DataFrame({})
# Perform the online write push
client_store.push(
push_source_name="driver_stats_push_source", df=event_df, to=PushMode.ONLINE
)
```