bugfix/multi placeholder and struct args

[zeroXbrock]

• feat: add uni v3 scenario

Fixed some bugs in the templating engine: structs as tuples were not supported. You can flatten tuples to get a signature that still works, so now we flatten function signatures with tuples (e.g. function set(uint x, (uint y, uint z)) becomes function set(uint x, uint y, uint z). The only modification needed to the UniV3 example was to flatten the args passed. The generator still expects the args to match the signature, and now that it's flattened, the args have to match that. But I think this is a fair compromise; it's easier to read when looking at args directly.

• fix arg replacement index bug in templater
• update packages
• flatten struct (tuple) args in fn sig to parse correctly
• flatten UniV3 scenario args