feat: target Gravity Bridge module

[facundomedica]

This PR aims to start using the Gravity module instead of the Peggy module.

• Tests are running and all features are working so far.
• Test coverage decreased a little, but that'll be solved in future PRs.

[codecov-commenter]

Codecov Report

Merging #118 (50c8d62) into main (ea8b3e4) will decrease coverage by 4.81%.
The diff coverage is 44.51%.

@@            Coverage Diff             @@
##             main     #118      +/-   ##
==========================================
- Coverage   65.12%   60.31%   -4.82%     
==========================================
  Files          17       17              
  Lines        1709     1862     +153     
==========================================
+ Hits         1113     1123      +10     
- Misses        518      661     +143     
  Partials       78       78              

Impacted Files	Coverage Δ
orchestrator/oracle_resync.go	0.00% <0.00%> (-100.00%)	⬇️
orchestrator/relayer/main_loop.go	0.00% <0.00%> (ø)
orchestrator/main_loops.go	10.40% <3.22%> (-0.04%)	⬇️
...hestrator/ethereum/gravity/pending_transactions.go	55.55% <71.42%> (ø)
orchestrator/relayer/find_latest_valset.go	73.57% <81.25%> (+0.38%)	⬆️
orchestrator/relayer/batch_relaying.go	73.14% <81.81%> (ø)
orchestrator/ethereum/gravity/submit_batch.go	85.14% <86.66%> (ø)
orchestrator/ethereum/gravity/peggy_contract.go	69.81% <87.50%> (ø)
orchestrator/relayer/valset_relaying.go	69.41% <91.66%> (ø)
orchestrator/cosmos/broadcast.go	93.17% <92.85%> (-0.04%)	⬇️
... and 7 more