Optimize tuple deepcopy

[DifferentialOrange]

After #268, input tuple is copied so we won't damage the original one. Performance has dropped by 5%.

Raw thoughts on possible optimizations:

• Skip copying on crud.insert_object().
• Pass the bucket_id separately to storage and insert it into the tuple on the storage (take care to router/storage rolling code update).

I don't want to change it within this pull request, but rather to think around later.

Originally posted by @Totktonada in #268 (comment)

[Totktonada]

NB: PR #232 also adds tuples copying to safely set bucket_id. I hope we can pass unchanges tuples to storages together with array of bucket_ids. Don't know, whether it'll be profitable, so we should do performance measurements.

See also #232 (comment).