calculate_hash: Calculate a Hash for Multiple Objects
Description
Calls digest::digest() using the 'xxhash64' algorithm after applying hash_input to each object.
To customize the hashing behaviour, you can overwrite hash_input for specific classes.
For data.table objects, hash_input is applied to all columns, so you can overwrite hash_input for
columns of a specific class.
Objects that don't have a specific method are hashed as is.