chore: math lib update and type fixes (#12791)

## Description

Upgrades the math library in the repo root and find/replaces many usages of sdk.Dec, sdk.ZeroDec, sdk.OneDec, sdk.NewDec with their legacy-ified-math-lib replacements.

Note for review: I assume that I did not find 100% of usages

---

### Author Checklist

*All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.*

I have...

- [ ] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] added `!` to the type prefix if API or client breaking change
- [ ] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/main/CONTRIBUTING.md#pr-targeting))
- [ ] provided a link to the relevant issue or specification
- [ ] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/main/docs/building-modules)
- [ ] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/main/CONTRIBUTING.md#testing)
- [ ] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification
- [ ] reviewed "Files changed" and left comments if necessary
- [ ] confirmed all CI checks have passed

### Reviewers Checklist

*All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.*

I have...

- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed 
- [ ] reviewed state machine logic
- [ ] reviewed API design and naming
- [ ] reviewed documentation is accurate
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)

api/cosmos/distribution/v1beta1/distribution.pulsar.go

@@ -7015,7 +7015,7 @@ func (x *CommunityPoolSpendProposal) GetAmount() []*v1beta1.Coin {
 // staking token, and the creation height (to check later on if any slashes have
 // occurred). NOTE: Even though validators are slashed to whole staking tokens,
 // the delegators within the validator may be left with less than a full token,
-// thus sdk.Dec is used.
+// thus math.LegacyDec is used.
 type DelegatorStartingInfo struct {
 	state         protoimpl.MessageState
 	sizeCache     protoimpl.SizeCache