[Feature]: implement mutative methods for sdk.DecCoins

[p0mvn]

Summary

For performance reasons, it would be nice to have mutative versions of MulDecTruncate and alike

ref: osmosis-labs/osmosis#7416 (comment)

Problem Definition

No response

Proposed Feature

Imlement mutative version for each math method on sdk.DecCoins

[alexanderbez]

Something tells me this is a duplicate issue. I feel like we've discussed this before and for some reason opted to close it...

[julienrbrt]

Something tells me this is a duplicate issue. I feel like we've discussed this before and for some reason opted to close it...

Yes, it the other issue was about sdk.Dec but not sdk.DecCoins