R4R: limit unbonding delegation / redelegations

[rigelrozanski]

closes #3270

• 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 #3372 into develop will increase coverage by 0.5%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           develop    #3372     +/-   ##
==========================================
+ Coverage    58.86%   59.37%   +0.5%     
==========================================
  Files          131      131             
  Lines         9836     9831      -5     
==========================================
+ Hits          5790     5837     +47     
+ Misses        3671     3621     -50     
+ Partials       375      373      -2

[cwgoes]

ACK, just a few typos

[alexanderbez]

ditto on a few typos, otherwise LGTM.