fix(launch): remove pointer for InitialGenesis in MsgCreateChain

[lumtis]

I realize adapting the CLI to the recent update, it is better to not use a pointer for InitialGenesis

[codecov]

Codecov Report

Merging #960 (c872067) into develop (142531a) will increase coverage by 0.00%.
The diff coverage is 14.28%.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #960   +/-   ##
========================================
  Coverage    10.65%   10.65%           
========================================
  Files          272      272           
  Lines        65235    65229    -6     
========================================
+ Hits          6949     6952    +3     
+ Misses       58121    58113    -8     
+ Partials       165      164    -1     

Impacted Files	Coverage Δ
x/launch/types/chain.pb.go	1.37% <ø> (ø)
x/launch/types/msg_create_chain.go	72.09% <ø> (ø)
x/launch/types/tx.pb.go	0.54% <0.00%> (+<0.01%)	⬆️
x/campaign/keeper/msg_initialize_mainnet.go	94.54% <100.00%> (ø)
x/launch/keeper/chain.go	97.36% <100.00%> (ø)
x/campaign/simulation/store.go	83.10% <0.00%> (+2.02%)	⬆️