refactor: clean up small_program_shapes method

[DeVikingMark]

Motivation

I was looking through the code and spotted a TODO comment in crates/core/machine/src/shape/mod.rs for cleaning up the small_program_shapes() method.

Fixes #2172

Solution

Сleaned up the method by:

• Moving those hardcoded values to proper named constants
• Breaking up the code into smaller, more readable chunks
• Adding some docs to explain what the method actually does
• Removing that old TODO

PR Checklist

• Added Tests
• Added Documentation
• Breaking changes

[leruaa]

As mentioned in the pull request template, trivial PRs are generally not accepted to not encourage PR farming.

[DeVikingMark]

As mentioned in the pull request template, trivial PRs are generally not accepted to not encourage PR farming.

@leruaa
Salute Aurélien! I understand your policy, and I somewhat agree with it ngl, but the thing is that it's hard for me to understand what means a trivial PR, and I just want to clarify what changes you acknowledge as worth working with, with all respect!