[Bugfix] Convert Custom JSON Marshaling Codec to Amino Codec

[yun-yeo]

Summary of changes

follow: cosmos/cosmos-sdk#6842, cosmos/cosmos-sdk#6861

Lets merge this with SDK v0.39.1

Report of required housekeeping

• Github issue OR spec proposal link
• Wrote tests
• Updated relevant documentation (docs/)
• Added a relevant changelog entry: clog add [section] [stanza] [message]

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(FOR ADMIN) Before merging

• Added appropriate labels to PR
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)
• Confirm added tests are consistent with the intended behavior of changes
• Ensure all tests pass

[codecov]

Codecov Report

Merging #377 into develop will increase coverage by 0.00%.
The diff coverage is 88.88%.

@@           Coverage Diff            @@
##           develop     #377   +/-   ##
========================================
  Coverage    65.18%   65.19%           
========================================
  Files          116      116           
  Lines         5736     5726   -10     
========================================
- Hits          3739     3733    -6     
+ Misses        1777     1775    -2     
+ Partials       220      218    -2     

Impacted Files	Coverage Δ
x/auth/vesting/types/vesting_account.go	89.43% <88.88%> (+2.21%)	⬆️