ClankerHookV2

The ClankerHookV2 contract is the abstract base class that the V2 hooks inherit from. It's a slight upgrade of ClankerHook with the following changes:

• The maximum LP fee that users can specify is 10% instead of 30%.

• Mev Modules are able to set the applied LP fee for a swap, with a maximum fee of 80%. If the Mev Module is trying to set a fee that is lower than what the pool would normally set the fee to, the module's change is ignored. The modules can still only run for up to 2 minutes.

• At the time of token deployment, an external Pool Extension contract can be specified to be called during the Hook's afterSwap flow. The purpose of the extensions is to enable developers to perform per-swap fee automations such as: staking, buybacks of external tokens, and performance-based fee unlock thresholds. Only tokens deployed via the factory can add pool extensions.

The other major change is the formatting of the deployment config's PoolConfig.poolData and swap hookData encoding. The previous version of ClankerHook did not expect this data to be in a specific shape, but ClankerHookV2 expects the following format:

struct PoolInitializationData {
    address extension; // address of the pool extension
    bytes extensionData; // data to pass to the pool extension
    bytes feeData; // data to use to configure the pool's fees (specific to the hook)
}

It is now expected that swap hookData, if present, will be encoded in the following shape:

struct PoolSwapData {
    bytes mevModuleSwapData; // data to pass to the mev module
    bytes poolExtensionSwapData; // data to pass the the pool extension
}