Add Math.bigint in SC

[samuelmanzanera]

Description

Add Math.bigint in smart contract, converting a number into its bigint representation for a given number of decimals

Type of change

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

How Has This Been Tested?

The use case has been tested with the bridge to set EVM big int

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented 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
• Any dependent changes have been merged and published in downstream modules