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## Description
Changes the `sdk.Msg` interface method `GetSigners() []string` to `GetSigners() []sdk.AccAddress`
Closes: #9885
+change GetSigner return type
+defer address checking to each msg's `ValidateBasic` method
+clean up consistency/redundancy issues in validate basic
---
### Author Checklist
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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
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- [ ] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go code](https://blog.golang.org/godoc)
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- [ ] confirmed all CI checks have passed
### 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
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- [ ] manually tested (if applicable)
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