[contract] - Implement governance voting by stake

[Hydrax117]

Location: contracts/ax-token/src/lib.rs

Governance voting not stake-weighted.

Acceptance Criteria:

• Voting weight = stake amount
• Quadratic voting option
• Delegation support
• Vote escrow for lock incentive
• Snapshot voting

[Lurdings]

@Lurdings has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hello Maintainer I will love to work on this issue, can you please assign it to me.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Lurdings to this issue.