Implement workaround for SortedTroves edge case

[danielattilasimon]

This relates to the backend quirk outlined by #600, which has been partially addressed by e469beb, however since then another edge case has been discovered.

As @RickGriff noted:

We just had a user who had the lowest ICR trove in the system, trying to adjust his trove to go lower. The tx failed before broadcast - presumably because gas estimation didn't allow it.

I believe this is the edge case DeFiSaver found - and I mistakenly thought the solution outlined above also covered it. The problem is that for the last trove in the list, the addressOfLowestICRTrove is their own address - and the reinsertion first removes it before the insert. The system can't find it in the list, so starts at the opposite end, and runs out of gas.

The DefiSaver fix was to check for this specific edge case: if the trove is last in the list, use the 2nd last trove's address as both hints.

We should implement the same workaround in the SDK.

[github-actions]

🎉 This issue has been resolved in version @liquity/lib-ethers-v3.3.1 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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