[PR-210] Add named conditionals

Description

Problem: every time I use IsGt or a similar conditional, I'm scared of that stack operands may go in a wrong order. Also, it is a good practice for Lorentz to, when where are several values of the same type on stack, assign names for them, but our conditionals interfere with doing so because they require unnamed entities.

Solution: add conditionals which expect named entities and require explicit passing of compared entities names, e.g. #old <=. #new.

Related issue(s)

https://issues.serokell.io/issue/PR-210

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