[TM-323] Add `cutLorentzNonDoc`

Description

Problem: sometimes we need a piece of code to inherit documentation of another piece of code, but semantics of the former is achieved in alternative way (e.g. comes from outer lambda).

Solution: contract code still seems to be the most natural building block for documentation, thus I just add a function to cut all instructions except for documentation-related ones.

Related issue(s)

https://issues.serokell.io/issue/TM-323

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