refactor: Move validator voting restrictions from Msg handler to Keeper

[edk208]

Description

The previous validator voting restriction only handled an increase to voting power through the Msg Handler Delegate command. The following refactoring pull request moves the validator restriction code to the delegation.go Keeper. This will protect against greater than 20% voting power in delegate, redelegate, and create validator situations.

Tests performed:

• create-validator with 23% self delegation voting power - correctly fails
  Error: rpc error: code = InvalidArgument desc = recovered: validator power is over the allowed limit

• create-validator with 9% self delegation voting power - success

• increase delegation from 91% to 92% voting power - correctly fails

• delegate from 9% voting power to 16% - success

• delegate from 16% voting power to 23% - correctly fails

---

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 in the PR title
• added ! to the type prefix if API or client breaking change
• targeted the correct branch (see PR Targeting)
• provided a link to the relevant issue or specification
• followed the guidelines for building modules
• included the necessary unit and integration tests
• added a changelog entry to CHANGELOG.md
• included comments for documenting Go code
• 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 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)

[vegasmorph]

@YunSuk-Yeo

[edk208]

Hi @YunSuk-Yeo, if you are ok with these changes and merge the changes, could I also request that the terra-money/classic-core go.mod be adjusted to reflect the terra-money/cosmos-sdk commit? I can also make the changes to classic-core in another PR if this get's pulled in if you would prefer. Thank you!!

[GODoal]

@YunSuk-Yeo To avoid any confusion; will you also be doing the terra-money/classic-core go.mod adjustments to reflect this commit?

[aeuser999]

Thank you so much @YunSuk-Yeo for your very helpful review, recommendations, your graciousness, and for your work in helping to restore Terra v1 governance to all LUNA v1 holders who stake. Thank You.