fix(x/epochs): di wiring

[ammar-elsabe]

Description

Closes: #25420

• Changed the keeper type in x/epochs ModuleOutputs to be a pointer to the keeper stored in the AppModule
  • EpochsKeeper's type in simapp/app_di.go was updated to match
• Added a test to verify depinject finds and invokes setting hooks
• Documented how to wire x/epochs in the README

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 70.30%. Comparing base (23f1ff1) to head (d0873d0).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff            @@
##             main   #25425    +/-   ##
========================================
  Coverage   70.30%   70.30%            
========================================
  Files         828      822     -6     
  Lines       53818    53627   -191     
========================================
- Hits        37839    37705   -134     
+ Misses      15979    15922    -57     

Files with missing lines	Coverage Δ
simapp/app_di.go	78.89% <ø> (ø)
x/epochs/depinject.go	86.36% <100.00%> (-4.55%)	⬇️
x/epochs/module.go	63.26% <100.00%> (ø)

... and 10 files with indirect coverage changes

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[ammar-elsabe]

@aljo242 fixed the build