refactor: Use mocks for x/mint testing

[facundomedica]

Description

Ref: #12398

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[alexanderbez]

So now x/mint keeper pkg tests no longer rely on simapp correct?

[facundomedica]

So now x/mint keeper pkg tests no longer rely on simapp correct?

Yes. We still have to figure out how to stop running a full app for some other tests, like the one in x/mint/module_test.go; but that's a bigger problem that should be fixed when we get to mock Tendermint.

[codecov]

Codecov Report

Merging #12468 (ea82a89) into main (5ef43f4) will decrease coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main   #12468      +/-   ##
==========================================
- Coverage   65.54%   65.51%   -0.03%     
==========================================
  Files         687      687              
  Lines       71707    71707              
==========================================
- Hits        46999    46981      -18     
- Misses      22054    22075      +21     
+ Partials     2654     2651       -3     

Impacted Files	Coverage Δ
x/mint/keeper/migrator.go	0.00% <0.00%> (-71.43%)	⬇️
x/mint/keeper/genesis.go	0.00% <0.00%> (-40.00%)	⬇️
x/mint/keeper/keeper.go	62.50% <0.00%> (-14.29%)	⬇️
x/mint/keeper/querier.go	0.00% <0.00%> (-2.86%)	⬇️