Feat/oracle

[sh-cha]

TODO:
Due to oracle price from L1, there is no way to know the real update time on L2 side. We need to think about it.

1. we can add timestamp on slinky's OracleVoteExtension.

[codecov]

Codecov Report

Attention: Patch coverage is 49.40476% with 170 lines in your changes are missing coverage. Please review.

Project coverage is 50.19%. Comparing base (1af9f7e) to head (918a464).

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #53      +/-   ##
==========================================
- Coverage   50.29%   50.19%   -0.11%     
==========================================
  Files          49       53       +4     
  Lines        3547     3881     +334     
==========================================
+ Hits         1784     1948     +164     
- Misses       1401     1535     +134     
- Partials      362      398      +36     

Files	Coverage Δ
x/opchild/types/codec.go	100.00% <100.00%> (ø)
x/opchild/types/params.go	61.36% <100.00%> (+1.83%)	⬆️
x/opchild/keeper/keeper.go	82.27% <85.00%> (+0.61%)	⬆️
x/opchild/keeper/params.go	51.61% <50.00%> (-0.39%)	⬇️
x/opchild/l2slinky/aggregator.go	66.66% <66.66%> (ø)
x/opchild/types/tx.go	54.94% <0.00%> (-4.58%)	⬇️
x/opchild/keeper/msg_server.go	53.17% <0.00%> (-2.71%)	⬇️
x/opchild/client/cli/tx.go	59.04% <0.00%> (-5.75%)	⬇️
x/opchild/keeper/host_validator_store.go	66.66% <66.66%> (ø)
x/opchild/keeper/oracle.go	59.09% <59.09%> (ø)
... and 1 more

[beer-1]

LGTM