Add migration script to prune wasm codes

[pinosu]

Resolves #999

[codecov]

Codecov Report

Merging #1542 (598ecd2) into main (ae964a8) will decrease coverage by 0.38%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main    #1542      +/-   ##
==========================================
- Coverage   58.00%   57.63%   -0.38%     
==========================================
  Files          64       65       +1     
  Lines        8640     8696      +56     
==========================================
  Hits         5012     5012              
- Misses       3215     3271      +56     
  Partials      413      413              

Files Changed	Coverage Δ
x/wasm/keeper/keeper.go	80.82% <0.00%> (-6.23%)	⬇️
x/wasm/keeper/migrations.go	80.00% <0.00%> (-20.00%)	⬇️
x/wasm/migrations/v4/store.go	0.00% <0.00%> (ø)
x/wasm/types/wasmer_engine.go	0.00% <ø> (ø)