Add custom query handling for unbonding balances

[codchen]

Describe your changes and provide context

GetUnbondingDelegations is not part of the standard staking wasmbinding so to support it we either need to fork many additional repos or add it as a custom query. The former seems riskier in terms of blast radius so we are adding it as a custom query here.

Testing performed to validate your change

integration test with gringotts contract

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 61.47%. Comparing base (223a234) to head (257976c).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2031   +/-   ##
=======================================
  Coverage   61.47%   61.47%           
=======================================
  Files         264      264           
  Lines       24565    24566    +1     
=======================================
+ Hits        15101    15102    +1     
  Misses       8335     8335           
  Partials     1129     1129           

Files with missing lines	Coverage Δ
app/app.go	66.35% <100.00%> (+0.02%)	⬆️