feat: use generics to load a collection from store

[robert-zaremba]

Description

[codecov]

Codecov Report

Merging #2010 (f3cac6d) into main (7f05ad4) will decrease coverage by 6.81%.
The diff coverage is 44.63%.

@@            Coverage Diff             @@
##             main    #2010      +/-   ##
==========================================
- Coverage   75.38%   68.58%   -6.81%     
==========================================
  Files         100      116      +16     
  Lines        8025     9329    +1304     
==========================================
+ Hits         6050     6398     +348     
- Misses       1589     2453     +864     
- Partials      386      478      +92     

Impacted Files	Coverage Δ
util/store/unmarshal.go	0.00% <0.00%> (ø)
x/incentive/codec.go	47.82% <ø> (+9.89%)	⬆️
x/incentive/keeper/grpc_query.go	0.00% <0.00%> (ø)
x/incentive/keeper/hooks.go	0.00% <0.00%> (ø)
x/incentive/keeper/invariants.go	0.00% <0.00%> (ø)
x/leverage/keeper/incentive.go	0.00% <0.00%> (ø)
x/oracle/keeper/hooks.go	95.65% <ø> (ø)
x/incentive/keeper/genesis.go	1.61% <1.61%> (ø)
x/incentive/genesis.go	10.32% <3.70%> (-3.01%)	⬇️
x/incentive/keeper/iter.go	20.14% <7.76%> (ø)
... and 26 more

... and 1 file with indirect coverage changes

[gsk967]

LGTM