feat: add 4pool

[romanagureev]

New Pool Checklist

Pool Info

• Name: 4pool
• Base template: Factory plain-4-basic

4pool can not be created via factory since using USDC and USDT. Supports factory/plain-4/basic abi, except admin functions which are made for PoolProxy.

Tokens

FRAX

General Info

• Deployment address: 0x853d955aCEf822Db058eb8505911ED77F175b99e
• Link to the token source code: etherscan
• Link to the developer documentation:

Behaviours

1. On a successful transfer this token: returns True
2. On a failed transfer this token: reverts
3. Are there any special approval behaviors? No
4. Is there a transfer fee, or the capability to add a transfer fee in the future? No

• I have reviewed the documentation and source code for this token, checking for unexpected behaviours that could affect the pool.

USDC

General Info

• Deployment address: 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48
• Link to the token source code: etherscan
• Link to the developer documentation:

Behaviours

1. On a successful transfer this token: returns True
2. On a failed transfer this token: reverts
3. Are there any special approval behaviors? No
4. Is there a transfer fee, or the capability to add a transfer fee in the future? No

• I have reviewed the documentation and source code for this token, checking for unexpected behaviours that could affect the pool.

UST

General Info

• Deployment address: 0xa693B19d2931d498c5B318dF961919BB4aee87a5
• Link to the token source code: etherscan
• Link to the developer documentation:

Behaviours

1. On a successful transfer this token: returns True
2. On a failed transfer this token: reverts
3. Are there any special approval behaviors? No
4. Is there a transfer fee, or the capability to add a transfer fee in the future? No

• I have reviewed the documentation and source code for this token, checking for unexpected behaviours that could affect the pool.

USDT

General Info

• Deployment address: 0xdAC17F958D2ee523a2206206994597C13D831ec7
• Link to the token source code: etherscan
• Link to the developer documentation:

Behaviours

1. On a successful transfer this token: returns None
2. On a failed transfer this token: reverts
3. Are there any special approval behaviors? Approval must be zeroed before a new one
4. Is there a transfer fee, or the capability to add a transfer fee in the future? Fees won't be set.

• I have reviewed the documentation and source code for this token, checking for unexpected behaviours that could affect the pool.

Fees

1. Does this pool include tokens that are already handled by the fee burning process? LPBurner could be used to remove USDT/USDC or MetaBurner for FRAX.

2. Does this pool include tokens that are not currently being burned, but which can be handled by an already deployed burner? UST

3. Does this pool require deployment of any new burners? Removing both USDC and USDT could lower slippage.

Pre-review Checklist

• I have included a pooldata.json with accurate token addresses
• I have included a README.md with accurate token addresses
• I have added a workflow targetting this pool, and confirmed that all tests are passing within the CI
• I have run brownie test tests/forked --network mainnet-fork locally and confirmed that all tests are passing
• I have verified the fee burning process for this pool and opened a related pull request on curve-dao-contracts if needed

Reviewer Pre-deployment Checklist

• This PR contains a new workflow file, and the entire test suite is passing
• I have verified the success / failure behaviours for each token in this pool
• I have run brownie test tests/forked --network mainnet-fork locally and confirmed that all tests are passing
• I have verified the fee burning process for this pool and any related pull requests
• This pool makes no significant modifications to the core math OR has been reviewed personally by @michwill

Post-deployment Checklist

• I have deployed a LiquidityGaugeV4 contract for this pool
• I have deployed any required fee burner contracts
• I have added pool and gauge deployment addresses to the pooldata.json and README.md files within this PR
• I have opened a pull request on curve-docs to add the new deployment addresses to the documentation
• I have created a DAO vote to add the new gauge and enable/configure fee burning