refactor: use cosmossdk.io/math

[aljo242]

Closes #940

[codecov]

Codecov Report

Merging #941 (c357685) into develop (7a5771d) will increase coverage by 0.00%.
The diff coverage is 87.50%.

@@           Coverage Diff            @@
##           develop     #941   +/-   ##
========================================
  Coverage    10.60%   10.60%           
========================================
  Files          328      328           
  Lines        75537    75537           
========================================
+ Hits          8007     8012    +5     
+ Misses       67340    67337    -3     
+ Partials       190      188    -2     

Impacted Files	Coverage Δ
x/campaign/keeper/campaign_auction_event_hooks.go	58.18% <ø> (ø)
x/participation/simulation/simulation.go	0.00% <0.00%> (ø)
x/reward/simulation/simulation.go	0.00% <0.00%> (ø)
x/mint/types/minter.go	82.97% <50.00%> (ø)
x/participation/simulation/store.go	82.85% <66.66%> (ø)
pkg/types/signature_counts.go	100.00% <100.00%> (ø)
x/campaign/simulation/store.go	84.45% <100.00%> (+3.37%)	⬆️
x/campaign/types/params.go	76.19% <100.00%> (ø)
x/campaign/types/shares.go	100.00% <100.00%> (ø)
x/campaign/types/total_supply.go	100.00% <100.00%> (ø)
... and 11 more

[lumtis]

LGTM