Handle unnecessary file hashes

[dafyddstephenson]

To instantiate an InputDataset object whose source location is remote, a file_hash is required. With the internal testing, we observed people copying the input dataset instantiation cells from notebook 1 (where remote input datasets were used) and updating the location to a local path, without changing the file_hash attribute.

The file_hash attribute is not needed for local files (so there was no consequence), but if it is provided:

• C-Star should check the file hash and raise an error if it is incorrect
• The error should tell the user that they don't strictly need a file hash for a local file