ensure the event emits amount in units of base

[jrhea]

resolves #668

[coveralls]

coverage: 96.403%. remained the same
when pulling 7c6dbf4 on collectFeesEventUnit
into 516c95a on main.

[github-actions]

Hyperdrive Gas Benchmark

Benchmark suite	Current: 7c6dbf4	Previous: 516c95a	Deviation	Status
addLiquidity: min	1622 gas	1622 gas	0%	🟰
addLiquidity: avg	53777 gas	53804 gas	-0.0502%	✅
addLiquidity: max	98336 gas	98352 gas	-0.0163%	✅
checkpoint: min	1216 gas	1216 gas	0%	🟰
checkpoint: avg	48303 gas	48284 gas	0.0394%	🚨
checkpoint: max	99770 gas	99770 gas	0%	🟰
closeLong: min	1690 gas	1690 gas	0%	🟰
closeLong: avg	24961 gas	24927 gas	0.1364%	🚨
closeLong: max	114154 gas	114154 gas	0%	🟰
closeShort: min	1693 gas	1693 gas	0%	🟰
closeShort: avg	27798 gas	27859 gas	-0.2190%	✅
closeShort: max	102099 gas	108895 gas	-6.2409%	✅
initialize: min	1605 gas	1605 gas	0%	🟰
initialize: avg	179603 gas	179603 gas	0%	🟰
initialize: max	254125 gas	254125 gas	0%	🟰
openLong: min	736 gas	736 gas	0%	🟰
openLong: avg	55952 gas	55929 gas	0.0411%	🚨
openLong: max	195381 gas	195381 gas	0%	🟰
openShort: min	702 gas	702 gas	0%	🟰
openShort: avg	55389 gas	55423 gas	-0.0613%	✅
openShort: max	194882 gas	194882 gas	0%	🟰
redeemWithdrawalShares: min	1598 gas	1598 gas	0%	🟰
redeemWithdrawalShares: avg	22307 gas	22307 gas	0%	🟰
redeemWithdrawalShares: max	49538 gas	49538 gas	0%	🟰
removeLiquidity: min	1661 gas	1661 gas	0%	🟰
removeLiquidity: avg	79592 gas	79639 gas	-0.0590%	✅
removeLiquidity: max	205229 gas	205229 gas	0%	🟰

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