Remove unused NegotiateAppVersion ibc callback

[alpe]

Now applications will perform this version negotiation during the channel handshake, thus removing the need for NegotiateAppVersion.

https://github.com/cosmos/ibc-go/blob/main/docs/migrations/v2-to-v3.md#negotiateappversion-removed-from-ibcmodule-interface

[codecov]

Codecov Report

Merging #879 (f6ca36f) into main (4525d51) will increase coverage by 0.05%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #879      +/-   ##
==========================================
+ Coverage   59.14%   59.19%   +0.05%     
==========================================
  Files          51       51              
  Lines        6198     6196       -2     
==========================================
+ Hits         3666     3668       +2     
+ Misses       2265     2262       -3     
+ Partials      267      266       -1     

Impacted Files	Coverage Δ
x/wasm/ibc.go	69.51% <ø> (+0.83%)	⬆️
x/wasm/keeper/keeper.go	88.57% <0.00%> (+0.33%)	⬆️

[ethanfrey]

Good catch