[BOOST-4672] implement flexible fee structures for `QuestBudget`

[mmackz]

Management Fee Implementation for QuestBudget

Overview

This PR implements the management fee feature for the QuestBudget contract, allowing boost creators to earn a fee for managing boosts.

Key Changes

1. Management Fee Setting:

   • Added setManagementFee function to allow the contract owner to set the management fee percentage.
   • Implemented managementFee state variable to store the fee percentage.

2. Boost Creation with Management Fee:

   • Modified createERC20Quest to calculate and reserve the management fee during quest creation.
   • Added reservedFunds state variable to track funds reserved for management fees.
   • Updated available function to account for reserved funds.

3. Management Fee Payment:

   • Implemented payManagementFee function to allow boost creators to claim their management fee after completion.
   • Added checks to ensure only the boost creator can claim the fee and only after the remaining rewards have been withdrawn.

4. Manager Tracking:

   • Added questManagers mapping to associate quest IDs with their creators' addresses.

5. Events:

   • Added ManagementFeeSet event for logging changes to the management fee percentage.
   • Added ManagementFeePaid event for logging management fee payments.

6. Testing:

   • Implemented comprehensive test suite for new management fee functionality.
   • Added helper functions and structs to streamline quest creation using common parameters.

Implementation Details

• The management fee is set in basis points (e.g., 500 = 5%).
• The maximum management fee that can be set is 10000 (100%)
• The fee is calculated based on the actual number of participants rather than the total possible participants.
• Reserved funds are tracked separately to ensure accurate reporting of available funds.
• Safeguards are in place to prevent unauthorized fee claims and to handle edge cases like insufficient funds.

Security Considerations

• The setManagementFee function is restricted to the contract owner.
• The payManagementFee function includes checks to prevent unauthorized claims.
• The contract uses OpenZeppelin's SafeERC20 for secure token transfers.

Testing

• Setting and updating the management fee
• Creating quests with management fees
• Paying out management fees under various scenarios
• Edge cases such as insufficient funds and unauthorized access attempts