feat: add data request incentives

[mariocao]

Motivation

This PR implements fee management functionality in the SEDA Core contract, allowing for:

• Request fees with gas-based refunds (derived from data results)
• Result fees for result solvers
• Batch fees for batch solver
• Support of fee increases for pending requests

Explanation of Changes

The changes introduce several key components:

• Added fee distribution logic in postResult function
• Implemented gas-based refund mechanism for request fees
• Added increaseFees function to allow updating fees for pending requests
• Added batch sender tracking for proper fee distribution
• Introduced RequestDetails struct to efficiently store fee-related data
• Added relevant events for fee distribution tracking
• Updated interfaces to support fee functionality

Testing

The changes are covered by comprehensive tests:

• Fee distribution logic
• Gas-based refund calculations
• Fee increase functionality
• Event emission verification
• Edge cases and error conditions

Related PRs and Issues

Closes #77
Closes #78
Closes #79
Closes #80

[gluax]

The code logic looks good to me.

I'm going to nit on the comments as the auditors want comment coverage.
Some of the comments describe what the code is doing. Which should only be done if something complex is happening, which I don't think most of this is.
Comments should describe why the code is doing what it's doing. This helps maintain readability and understanding more than stating what something is doing.

The comments on functions and types are good though :).

[gluax]

Comments looking much better!!

[FranklinWaller]

Nothing to fix here but we should really have a wrapper or something to simplify the 3 fees and the rest of the inputs properties. (even if the user is overpaying, they'll get it refunded.)