Calculate reserve auction price using kicked amount

Description

Contradicting the whitepaper, Claimable Reserve Auctions (CRAs) originally had a pricing mechanism with a start price of 1 quote token for 1bbn AJNA. This was done to simplify the auction mechanism, but the whitepaper was not updated to reflect the implementation. Kirill's audit brought this up with issue M-01. Upon initial review we favored the original implementation and chose to update the whitepaper. This decision was challenged during the fix review.

The original implementation naturally prevented 0-bids, as the pricing function would not reach 0 after 72 hours. Since the amount of claimable reserves is now part of the formula, we can no longer guarantee this. As such, an explicit check has been added to ensure at least 1 wei of AJNA is burned. This change necessitated improvement in logic handling bids for less than the quote token's trading increment.

To reduce cost of updating unit tests, RewardsManager tests are now skipped. Removal of RewardsManager may be covered by a separate PR.

Note that the author is not necessarily in agreement with this change.

Purpose

(versus updating whitepaper)

Pros

CRAs will reach a fair market price more quickly

Cons

additional gas cost for kicking, exascerbated by removal of the kick reward in this release
added maintenance complexity
CRAs will reach an infinitessimal price where they may be almost-zero-bid upon more quickly

Impact

Pool contract sizes are similar. 2.3x gas cost for kicking, due to writing to an additional storage slot. Trivial increase in gas cost for taking.

Tasks

[x] Changes to protocol contracts are covered by unit tests executed by CI.
[x] Protocol contract size limits have not been exceeded.
[x] Gas consumption for impacted transactions have been compared with the target branch, and nontrivial changes cited in the Impact section above.
[x] Scope labels have been assigned as appropriate.
[ ] Invariant tests have been manually executed as appropriate for the nature of the change.

ajna-finance / ajna-core