Two Variable Gradual Dutch Auction Module

[Oighty]

Implement a two variable gradual dutch auction based on the math in this (draft) post:

Could make various combinations of linear and exponential decay (4 total combinations between variables), but this may be overkill. If using a version of the equation that incorporates minimum price directly (versus truncating with a minimum value), then linear decay must be used on the price variable. Likely, it's best to do linear decay only on price and have an option on the other variable.

Use case: Vesting curve auctions which match supply of vesting durations with demand. Replaces SDAs with a set vesting duration for protocols looking to "bond".

An initial version was started in src/modules/auctions/TVGDA.sol, but is not complete and has carry over from the GDA file.