Make `IsoValue` for extended lambdas saner

Description

Problem: currently fromVal . toVal is not id, thus for code which uses extended lambdas (e.g. PermanentImpl) there might be produced extra instructions.

In particular, this is a problem for one of our projects, because now roundtrip test fails there due to use of PermanentImpl.

Solution: make ## optimize out such cases.

Previously this operator has been moved to Lorentz.Base, but I moved it back because it is a sort of hack (we have optimize function for public use) and optimizations which it applies depend on concrete situation.

Related issue(s)

Resolves #

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