R4R: added macos integration tests

[mircea-c]

Closes #2498

• 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 #3152 into develop will decrease coverage by 0.01%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop    #3152      +/-   ##
===========================================
- Coverage    55.03%   55.01%   -0.02%     
===========================================
  Files          133      133              
  Lines         9427     9434       +7     
===========================================
+ Hits          5188     5190       +2     
- Misses        3922     3927       +5     
  Partials       317      317

[mircea-c]

Only running the basic integration test and fast simulation, can add more if required.

I think we should also only run this on develop and master branch as we have a limited amount of minutes for macos testing right now. I haven't implemented that filtering as of yet, but it's a simple change.

[mircea-c]

Changed my mind, added branch filtering from the get go. Successful tests of the macos ci can be found here:

https://circleci.com/gh/cosmos/cosmos-sdk/61434

[jackzampolin]

I think we just want to test that the binary compiles on mac, which this does. Not against also running basic tests on mac too, but this looks good.

[mircea-c]

Great. I removed the examples tests. I'm leaving the integration and fast sim for sanity 😄

[jackzampolin]

Mo tests, mo betta

[cwgoes]

ACK, great to test this now - thanks @mircea-c!