[VEN-2843] Upgrade implementation of vToken contracts

[web3rover]

Description

Resolves #

Checklist

• I have updated the documentation to account for the changes in the code.
• If I added new functionality, I added tests covering it.
• If I fixed a bug, I added a test preventing this bug from silently reappearing again.
• My contribution follows Venus contribution guidelines.

[github-actions]

Package	Line Rate	Branch Rate	Health
contracts	94%	76%	✔
contracts.Gateway	98%	68%	✔
contracts.Gateway.Interfaces	100%	100%	✔
contracts.Lens	95%	71%	✔
contracts.Lens.legacy	0%	0%	❌
contracts.Pool	100%	92%	✔
contracts.Rewards	96%	70%	✔
contracts.Shortfall	100%	85%	✔
contracts.legacy.RiskFund	0%	0%	❌
contracts.lib	100%	89%	✔
Summary	76% (1557 / 2055)	65% (516 / 798)	➖