test: adding test cases for participationrewards

[muku314115]

1. Summary

Fixes #366
Note: CalcOverallScores never returns the error, instead it logs it and moves on, this behaviour has been changed in the PR to return the error in which case the getZoneScores function will stop on encountering any problem with overall score calculation

2.Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

3. Implementation details

4. How to test/use

5. Checklist

• Does the Readme need to be updated?

6. Limitations (optional)

7. Future Work (optional)

[aljo242]

structure looks good

[codecov-commenter]

Codecov Report

Merging #457 (c76ffd9) into develop (572115a) will increase coverage by 0.67%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           develop     #457      +/-   ##
===========================================
+ Coverage    54.98%   55.66%   +0.67%     
===========================================
  Files          164      164              
  Lines        12337    12364      +27     
===========================================
+ Hits          6784     6882      +98     
+ Misses        5035     4969      -66     
+ Partials       518      513       -5     

Flag	Coverage Δ
unittests	55.66% <100.00%> (+0.67%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
x/interchainstaking/keeper/grpc_query.go	81.69% <100.00%> (+1.19%)	⬆️
x/interchainstaking/keeper/withdrawal_record.go	82.87% <100.00%> (+2.44%)	⬆️
x/participationrewards/keeper/rewards_lockup.go	100.00% <100.00%> (ø)
...pationrewards/keeper/rewards_validatorSelection.go	93.90% <100.00%> (+29.29%)	⬆️

... and 1 file with indirect coverage changes

[aljo242]

@muku314115 just lint failing

[joe-bowman]

looks good, but requires linting + gofumpt

[joe-bowman]

lgtm