refactor!: move x/staking Init/Export genesis to keeper

[alexanderbez]

Description

Move InitGenesis and ExportGenesis to the Keeper type for x/staking as they had no business being separate functions outside the keeper type.

cc @ValarDragon

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• confirmed the correct type prefix in the PR title
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[ValarDragon]

This is awesome! Looking forward to so much public API surface decreasing from these keepers

[likhita-809]

@alexanderbez I think we also need to move the related genesis tests to keeper and we need to fix the failing tests because of staking imports in other modules.

[codecov]

Codecov Report

Merging #11866 (c53208c) into main (35d3312) will decrease coverage by 0.03%.
The diff coverage is 52.98%.

@@            Coverage Diff             @@
##             main   #11866      +/-   ##
==========================================
- Coverage   66.05%   66.02%   -0.04%     
==========================================
  Files         705      671      -34     
  Lines       73614    70718    -2896     
==========================================
- Hits        48625    46689    -1936     
+ Misses      22051    21359     -692     
+ Partials     2938     2670     -268     

Impacted Files	Coverage Δ
x/staking/genesis.go	46.15% <ø> (-12.00%)	⬇️
x/staking/module.go	64.78% <50.00%> (+0.89%)	⬆️
x/staking/keeper/genesis.go	53.03% <53.03%> (ø)
x/distribution/simulation/operations.go	80.54% <0.00%> (-9.73%)	⬇️
orm/encoding/ormkv/unique_key.go
orm/model/ormtable/unique.go
orm/model/ormtable/auto_increment.go
orm/encoding/ormfield/uint64.go
orm/model/ormdb/json.go
... and 35 more