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## Description
Adds the amount of coins slashed from the validator to the `Slash` event. Additionally, before this PR, the jail/slash events were emitted **BEFORE** the slash/jail functions were even ran, which could result in a false positive event if an error occurred in these functions. ~~These events were moved to the end of the functions that implement the logic for them instead.~~ This PR moves the events to be emitted after the logic is executed.
Closes: #9138
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- +Add `amount_slashed` to slash event
- +Slash now returns the amount of tokens burned
- +Events moved to be emitted after the logic is executed
- +Add test to test the slash return amount
~~- +Add EventType `Jail` to separate it from the `Slash` event~~
~~- +Move slash/jail events into the functions that execute the logic for it~~
~~- -Remove `Reason` attribute from slash event (didn't appear to be consistent with what was happening in code)~~
### 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
- [x] 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)
- [x] updated the relevant documentation or specification
- [x] reviewed "Files changed" and left comments if necessary
- [x] confirmed all CI checks have passed
### Reviewers Checklist
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your handle next to the items reviewed if you only reviewed selected items.*
I have...
- [x] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title - @ryanchristo
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed
- [x] reviewed state machine logic - not applicable
- [x] reviewed API design and naming - @ryanchristo
- [x] reviewed documentation is accurate - @ryanchristo
- [x] reviewed tests and test coverage - @ryanchristo
- [ ] manually tested (if applicable)
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