* Move snapshotstore under store
* add changelog entry
* errors store
* remove dep on sdk/types/errors
* clean up
* fix var
* undo some changes, clean up fmt.Errorf usage
* remove pkg/errors
Moves the separate repos for ICS23 proof tooling into `store/tools`
I've set `github.com/confio/ics23/go` to version 0.7.0 in anticipation of https://github.com/confio/ics23/pull/61 being merged, as it's a dependency for SMT proofs, so this shouldn't be merged until that version exists.
Closes: https://github.com/cosmos/cosmos-sdk/issues/10801
---
### Author Checklist
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please add links to any relevant follow up issues.*
I have...
- [x] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [x] added `!` to the type prefix if API or client breaking change
- [x] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#pr-targeting))
- [x] provided a link to the relevant issue or specification
- [ ] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/master/docs/building-modules)
- [x] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#testing)
- [ ] added a changelog entry to `CHANGELOG.md`
- [x] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification
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### Reviewers Checklist
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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
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- [ ] manually tested (if applicable)
