R4R: Add JSON Struct Tags to Vesting Accounts

[alexanderbez]

closes: #3648

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• Targeted PR against correct branch (see CONTRIBUTING.md)

• Linked to github-issue with discussion and accepted design OR link to spec that describes this work.

• Wrote tests

• Updated relevant documentation (docs/)

• Added entries in PENDING.md with issue #

• rereviewed Files changed in the github PR explorer

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For Admin Use:

• Added appropriate labels to PR (ex. wip, ready-for-review, docs)
• Reviewers Assigned
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)

[codecov]

Codecov Report

Merging #3651 into develop will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop    #3651   +/-   ##
========================================
  Coverage    60.92%   60.92%           
========================================
  Files          188      188           
  Lines        14084    14084           
========================================
  Hits          8581     8581           
  Misses        4959     4959           
  Partials       544      544

[cwgoes]

ACK