feat: use scarb macro to generate const powers

[juankohler]

Pull Request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Build-related changes
• Documentation content changes
• Other (please describe):

What is the current behavior?

Resolves: #841

What is the new behavior?

• Uses pow! macro instead of hardcoded constants.

Does this introduce a breaking change?

• Yes
• No

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This change is 

[juankohler]

Hi @enitrat, I have a problem. When I took the issue, I interpreted that I needed to export the Alexandria package, but then I realized that it was in Rust. When I looked into how to calculate the power of 2 at compile time in Cairo, I couldn't find any solution. The current utils only calculate at runtime up to 128. The only way I can think of is to hardcode the constants up to that number and create a function that returns them depending on the argument passed, but this doesn't seem like an optimal solution. Could you help me with this?

[enitrat]

I don't understand the problem. Can't you use the macro?

[enitrat]

merge blocked until snfoundry allows use of scarb macros