fix: add validation for potential slashing evasion during re-delegation

[ulbqb]

Description

closes: #XXXX

According to the GHSA-86h5-xcpx-cfqc, an issue was identified in the slashing mechanism that may allow for the evasion of slashing penalties during a slashing event. If a delegation contributed to the byzantine behavior of a validator and the validator has not yet been slashed, it may be possible for that delegation to evade a pending slashing penalty through re-delegation behavior.

Additional validation logic was added to restrict this behavior in below commit in cosmos-sdk.
cosmos/cosmos-sdk@d1b5b0c

Motivation and context

How has this been tested?

Screenshots (if appropriate):

Checklist:

• I followed the contributing guidelines and code of conduct.
• I have added a relevant changelog to CHANGELOG.md
• I have added tests to cover my changes.
• I have updated the documentation accordingly.
• I have updated API documentation client/docs/swagger-ui/swagger.yaml

[codecov]

Codecov Report

Attention: Patch coverage is 6.89655% with 27 lines in your changes are missing coverage. Please review.

Project coverage is 70.41%. Comparing base (e986f03) to head (6afe0d4).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1306      +/-   ##
==========================================
- Coverage   70.42%   70.41%   -0.02%     
==========================================
  Files         643      643              
  Lines       54730    54758      +28     
==========================================
+ Hits        38546    38560      +14     
- Misses      14011    14023      +12     
- Partials     2173     2175       +2     

Files	Coverage Δ
simapp/app.go	79.16% <0.00%> (-2.09%)	⬇️
x/staking/keeper/slash.go	63.52% <9.52%> (-7.71%)	⬇️

... and 3 files with indirect coverage changes