Accumulator package: Use pointers, save repeated gets

[ValarDragon]

In the accumulator package, we do repeated gets in several locations. This is because we are not using pointers for the base of functions, so mutations are not getting tracked correctly.

We should make GetAccumulator return a pointer, and then we can save redundant state operations, such as right here: https://github.com/osmosis-labs/osmosis/blob/main/osmoutils/accum/accum.go#L151-L155

This should with execution time and gas costs.

[czarcas7ic]

Changing status back to "In Progress" from "Done" since it appears the PR linked was only a component. Are you able to list out further components so we can get these knocked out?

[ValarDragon]

Going to close for now! I'll make a new issue if I see more