Archive Node Migration: Expose Get State Store + Query Iavl Before Migration Height

[Kbhat1]

Describe your changes and provide context

• Exposes GetStateStore from rootmulti
• For historical queries, if before migration height, points to iavl

Testing performed to validate your change

• Verified and tested on node

[codecov]

Codecov Report

Attention: Patch coverage is 39.53488% with 26 lines in your changes missing coverage. Please review.

Project coverage is 54.89%. Comparing base (4e7d467) to head (468f8dc).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
baseapp/abci.go	62.96%	7 Missing and 3 partials ⚠️
baseapp/baseapp.go	0.00%	6 Missing and 2 partials ⚠️
baseapp/options.go	0.00%	4 Missing ⚠️
storev2/rootmulti/store.go	0.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #541      +/-   ##
==========================================
- Coverage   54.90%   54.89%   -0.01%     
==========================================
  Files         631      631              
  Lines       54920    54955      +35     
==========================================
+ Hits        30152    30166      +14     
- Misses      22614    22631      +17     
- Partials     2154     2158       +4     

Files with missing lines	Coverage Δ
baseapp/options.go	46.78% <0.00%> (-1.13%)	⬇️
storev2/rootmulti/store.go	2.60% <0.00%> (-0.01%)	⬇️
baseapp/baseapp.go	65.66% <0.00%> (-0.68%)	⬇️
baseapp/abci.go	52.79% <62.96%> (+0.27%)	⬆️