Investigate and fix unwanted storage of junk/invalid data in `DataStoreLevel` implementation

[Henry Tsai]

There appears a bug in DataStoreLevel.put() implementation where if there exists a piece of data with dataCid X in the store, and another put()is called with the same tenantId and dataCid X but incorrect data stream, this incorrect data would be stored indefinitely as chunks.

A potential way to fix this is to:

1. push the dataCid check currently done by the caller of put() into put() itself.
2. attempt to see if an existing data with dataCid X is in the store, if in this store, then read the data stream into a temporary location (to be deleted later). If not in the store, then proceed to happy/common path (also require code tweaks in this path.
3. validate the dataCid of data in temporary location and react accordingly.