Improving Trigger Orders

[crispheaney]

I recommend the following improvements to make trigger orders better for drift protocol users:

1. Add a new TriggerOracle order type to replace TriggerMarket. Trigger oracle orders will use oracle offsets for the auction price, which will make them more dynamic and thus more likely to fill when volatility is high and oracle is moving quickly
2. Skip canceling trigger orders immediately when liquidations are initiated and allow them to be filled even during on-going liquidation

The goal of #1's is to give stop losses/take profits better auction params, leading to better exit prices. An implementation for this has been started here: #677

The goal of #2 is alleviate the issue where the oracle wicks and liquidation cancels trigger orders before they can be triggered and filled. This is tricky, because the protocol can't completely block liquidations to wait for stops to fills, since there could be limited liquidity and orders might not be able to fill. Thus the compromise (at least for now) is to let the trigger orders fill while the liquidations are on-going.

Since the liquidations and filler/trigger bots will be competing to land tx (the former to do liquidation, the latter to trigger and fill user order), we can optionally make a third improvement:

3. Have default filler/trigger bot implementations set a higher priority fee for users in liquidation with trigger orders