stETH Integration

[jalextowle]

This PR implements a direct stETH integration. Most of the code for this integration was able to be taken from commits prior to #454. This PR accomplishes two primary goals:

1. Having as efficient of a stETH integration as possible (pass-through vaults add significant overhead).
2. Supporting ETH deposits for the stETH integration.

Aside from implementing the stETH integration, this PR also re-organized the instances directory. In particular, instances are now grouped into sub-folders, and there is a new directory called deployers which contains the deployer implementations for each instance.

In addition to these other changes, this PR implements the infrastructure that will be required to run a testnet with both a stETH and an sDAI pool.

[coveralls]

coverage: 95.257% (+0.02%) from 95.238%
when pulling 9740c9a on jalextowle/instance/steth-2
into c2e0f6c on main.

[github-actions]

Hyperdrive Gas Benchmark

Benchmark suite	Current: 9740c9a	Previous: aadaa99	Deviation	Status
addLiquidity: min	1600 gas	1600 gas	0%	🟰
addLiquidity: avg	65855 gas	55098 gas	19.5234%	🚨
addLiquidity: max	275046 gas	232446 gas	18.3268%	🚨
checkpoint: min	1172 gas	1172 gas	0%	🟰
checkpoint: avg	47965 gas	47937 gas	0.0584%	🚨
checkpoint: max	202123 gas	202123 gas	0%	🟰
closeLong: min	1580 gas	1580 gas	0%	🟰
closeLong: avg	27883 gas	26510 gas	5.1792%	🚨
closeLong: max	148684 gas	139624 gas	6.4889%	🚨
closeShort: min	1549 gas	1549 gas	0%	🟰
closeShort: avg	29960 gas	28777 gas	4.1109%	🚨
closeShort: max	147189 gas	144389 gas	1.9392%	🚨
initialize: min	1538 gas	1538 gas	0%	🟰
initialize: avg	214974 gas	181786 gas	18.2566%	🚨
initialize: max	256760 gas	256760 gas	0%	🟰
openLong: min	1509 gas	1509 gas	0%	🟰
openLong: avg	50164 gas	40502 gas	23.8556%	🚨
openLong: max	185904 gas	162207 gas	14.6091%	🚨
openShort: min	1519 gas	1519 gas	0%	🟰
openShort: avg	47447 gas	47335 gas	0.2366%	🚨
openShort: max	161536 gas	161536 gas	0%	🟰
redeemWithdrawalShares: min	1575 gas	1575 gas	0%	🟰
redeemWithdrawalShares: avg	23597 gas	18465 gas	27.7931%	🚨
redeemWithdrawalShares: max	105958 gas	84767 gas	24.9991%	🚨
removeLiquidity: min	1661 gas	1661 gas	0%	🟰
removeLiquidity: avg	148181 gas	118880 gas	24.6475%	🚨
removeLiquidity: max	323560 gas	258848 gas	25%	🚨

This comment was automatically generated by workflow using github-action-benchmark.

[jrhea]

This looks good. I'm surprised that there was no gas savings, any idea why that is?

[jrhea]

lgtm