refactor: 1218 FPN unifies integers validation

[lucanicoladebiasi]

Description

The FPN class unifies the functions to check if textual expressions are signed/unsigned strictly positive or positive/negative integers.

Fixes # (issue)

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• yarn test:examples
• yarn test:solo
• yarn test:unit

Test Configuration:

• Node.js Version: v20.14.0
• Yarn Version: 1.22.22

Checklist:

• My code follows the coding standards of this project
• I have performed a self-review of my code
• I have commented on my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• New and existing integration tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• I have not added any vulnerable dependencies to my code

[github-actions]

Test Coverage

Summary

Lines	Statements	Branches	Functions
	99.5% (4035/4055)	98.2% (1259/1282)	99.87% (807/808)

Title	Tests	Skipped	Failures	Errors	Time
core	808	0 💤	0 ❌	0 🔥	1m 30s ⏱️
network	643	0 💤	0 ❌	0 🔥	3m 55s ⏱️
errors	42	0 💤	0 ❌	0 🔥	14.576s ⏱️