[oak] Use map[T]struct{}{} instead of map[T]bool for performance reason

[yzang2019]

Describe your changes and provide context

The alternative representation can be faster and more efficient in terms of memory.

This PR changes this representation of the hash map to a map[T]struct{}{} based on the results from https://itnext.io/set-in-go-map-bool-and-map-struct-performance-comparison-5315b4b107b.

Testing performed to validate your change

Existing unit test covers it

[github-actions]

Package	Line Rate	Complexity	Health
github.com/sei-protocol/sei-chain/aclmapping/bank	83%	0	✔
github.com/sei-protocol/sei-chain/aclmapping/dex	100%	0	✔
github.com/sei-protocol/sei-chain/aclmapping/oracle	100%	0	✔
github.com/sei-protocol/sei-chain/aclmapping/staking	82%	0	✔
github.com/sei-protocol/sei-chain/aclmapping/tokenfactory	96%	0	✔
github.com/sei-protocol/sei-chain/aclmapping/utils	0%	0	❌
github.com/sei-protocol/sei-chain/aclmapping/wasm	83%	0	✔
github.com/sei-protocol/sei-chain/app	60%	0	➖
github.com/sei-protocol/sei-chain/app/antedecorators	76%	0	✔
github.com/sei-protocol/sei-chain/oracle/price-feeder/config	85%	0	✔
github.com/sei-protocol/sei-chain/oracle/price-feeder/oracle	67%	0	➖
github.com/sei-protocol/sei-chain/oracle/price-feeder/oracle/provider	49%	0	❌
github.com/sei-protocol/sei-chain/oracle/price-feeder/router/v1	45%	0	❌
github.com/sei-protocol/sei-chain/store/whitelist/cachemulti	100%	0	✔
github.com/sei-protocol/sei-chain/store/whitelist/kv	100%	0	✔
github.com/sei-protocol/sei-chain/store/whitelist/multi	100%	0	✔
github.com/sei-protocol/sei-chain/utils	46%	0	❌
github.com/sei-protocol/sei-chain/utils/datastructures	90%	0	✔
github.com/sei-protocol/sei-chain/utils/logging	100%	0	✔
github.com/sei-protocol/sei-chain/x/dex	58%	0	➖
github.com/sei-protocol/sei-chain/x/dex/cache	87%	0	✔
github.com/sei-protocol/sei-chain/x/dex/client/cli/query	23%	0	❌
github.com/sei-protocol/sei-chain/x/dex/contract	51%	0	➖
github.com/sei-protocol/sei-chain/x/dex/exchange	89%	0	✔
github.com/sei-protocol/sei-chain/x/dex/keeper	63%	0	➖
github.com/sei-protocol/sei-chain/x/dex/keeper/abci	29%	0	❌
github.com/sei-protocol/sei-chain/x/dex/keeper/msgserver	78%	0	✔
github.com/sei-protocol/sei-chain/x/dex/keeper/query	82%	0	✔
github.com/sei-protocol/sei-chain/x/dex/migrations	88%	0	✔
github.com/sei-protocol/sei-chain/x/dex/types	1%	0	❌
github.com/sei-protocol/sei-chain/x/dex/types/utils	100%	0	✔
github.com/sei-protocol/sei-chain/x/dex/types/wasm	83%	0	✔
github.com/sei-protocol/sei-chain/x/epoch	11%	0	❌
github.com/sei-protocol/sei-chain/x/epoch/keeper	66%	0	➖
github.com/sei-protocol/sei-chain/x/epoch/types	2%	0	❌
github.com/sei-protocol/sei-chain/x/mint	0%	0	❌
github.com/sei-protocol/sei-chain/x/mint/keeper	61%	0	➖
github.com/sei-protocol/sei-chain/x/mint/simulation	95%	0	✔
github.com/sei-protocol/sei-chain/x/mint/types	3%	0	❌
github.com/sei-protocol/sei-chain/x/nitro/client/cli	45%	0	❌
github.com/sei-protocol/sei-chain/x/nitro/keeper	80%	0	✔
github.com/sei-protocol/sei-chain/x/nitro/replay	63%	0	➖
github.com/sei-protocol/sei-chain/x/oracle	67%	0	➖
github.com/sei-protocol/sei-chain/x/oracle/keeper	83%	0	✔
github.com/sei-protocol/sei-chain/x/oracle/simulation	18%	0	❌
github.com/sei-protocol/sei-chain/x/oracle/types	3%	0	❌
github.com/sei-protocol/sei-chain/x/tokenfactory/keeper	85%	0	✔
github.com/sei-protocol/sei-chain/x/tokenfactory/types	2%	0	❌
Summary	15% (5140 / 34223)	0	❌