feat(smart-contracts): UP/UDT swap contract

[clemsos]

Description

This is a contract to swap UDT for UP.

Unlock Labs is planning to submit a proposal to the DAO to "move" to Base. This includes deploying a new Governor Contract, a new Timelock contract, as well as a new governance token contract, called UPToken. (Unlock Protocol Token).
However, we want this new token to be a "replacement" for the legacy UDT contract, which means that the only way to "receive" UP tokens is to bridge UDT to Base and then send the UDT tokens to a Swap contract. The amount of UP tokens received is based on a fixed redeem rate of 1000 for 1.

We also want the contract to support the "opposite" operation that would let anyone who owns UP tokens redeem them for legacy UDT, as the inverse rate of 1000 for 1.

Issues

Fixes #
Refs #

Checklist:

• 1 PR, 1 purpose: my Pull Request applies to a single purpose
• I have commented my code, particularly in hard-to-understand areas
• I have updated the docs to reflect my changes if applicable
• I have added tests (and stories for frontend components) that prove my fix is effective or that my feature works
• I have performed a self-review of my own code
• If my code involves visual changes, I am adding applicable screenshots to this thread

Release Note Draft Snippet

[clemsos]

relates to #13875

[clemsos]

Tokens on Base Sepolia:

• UDT: https://sepolia.etherscan.io/address/0x447B1492C5038203f1927eB2a374F5Fcdc25999d
• UPToken: https://sepolia.basescan.org/address/0xc9F29DdBD4D828cFb2EB491E9d48013a9c0E3C89
• Swap contract: https://sepolia.basescan.org/address/0xaB82D702A4e0cD165072C005dc504A21c019718F

Try the workflow

1. Bridge UDT to Base Sepolia

• UDT on Sepolia: https://sepolia.etherscan.io/address/0x447B1492C5038203f1927eB2a374F5Fcdc25999d
• Bridge UDT: https://superbridge.app/base-sepolia

2. Swap UDT for UP token

• Approve Swap to spend UDT on Base Sepolia: https://sepolia.basescan.org/token/0x68a8011d72E6D41bf7CE9dC49De0aeaEBAAC9b39#writeContract
• Swap UDT for Up: https://sepolia.basescan.org/address/0xaB82D702A4e0cD165072C005dc504A21c019718F

example tx: https://sepolia.basescan.org/tx/0x024c51dc08912ed0403f9dc26b3f94e9dc760c0ce64fa9ce68acfe41f19fcdb3

[julien51]

ok @bytes032, this is the PR in which we're adding the contract to be audited. Please bear with us as we're cleaning this up!

[julien51]

@clemsos please confirm we need to rebase after #13875 has been merged?

[clemsos]

@clemsos please confirm we need to rebase after #13875 has been merged?

Yes I just merged and rebased

[julien51]

Hey @marvinkruse please check this PR regarding the audit!

[marvinkruse]

Hey @julien51 - thank you for tagging me, checking it out!