signer list set quorum fix

[florent-uzio]

Title

Description

This PR aims to:

• Updated SignerQuorum in SignerListSet to be a pointer (*uint32) instead of a value (uint32).
  • This allows distinguishing between an unset (nil) and an explicitly set value, including 0 to delete a signer list.
  • Ensures SignerQuorum is only included in the Flatten() output when explicitly defined.
  • Updates the Validate method to make sure SignerEntries is not set when SignerQuorum is set to 0

Type of change

• Bug fix
• New feature
• Breaking change
• Documentation update
• Refactoring

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 where needed
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective
• New and existing unit tests pass locally with my changes

Changes

• Change 1: SignerQuorum in SignerListSet to be a pointer (*uint32) instead of a value (uint32).
• Change 2: New error ErrInvalidQuorumAndEntries introduced

Notes (optional)

Describe any additional notes here.

[GuillemGarciaDev]

I refactored the SignerQuorum type to interface{} with uint32 type assertion in order to improve the developer experience.