Implement `Write` actions in contracts

[RyRy79261]

Overview

Currently, some of the write actions are not available.

This ticket is to create the necessary hooks for the available write actions. Simulation functions will also be needed.

Acceptance criteria

• Approve Mento transfer
  • [ ] Simulation function
  • [ ] Execute function
• Lock for veMento
  • [ ] Simulation function
  • [ ] Execute function
• Create proposal
  • [ ] Simulation function
  • [ ] Execute function
• Vote
  • [ ] Simulation function
  • [ ] Execute function

[bayological]

@RyRy79261 Vote is already implemented

[denviljclarke]

@RyRy79261, We can break this up. I'll implement the locking logic as I'm working on this issue which requires locking logic. You can then work on create proposal when you're ready.