Add arbitrum specific gateway contracts#7

Merged

jaybuidl merged 11 commits intomasterfrom

feature/gateway

Jan 20, 2022

Commits on Jan 3, 2022

feat(gateway): implement cross-chain evidence standard
shalzz
committed

Commits on Jan 4, 2022

feat(bridge): add xdai bridges
shalzz
committed

Commits on Jan 5, 2022

Commits on Jan 14, 2022

refactor(gateway): start the foreignDisputeID from 1
shalzz
committed

Commits on Jan 18, 2022

fix(gateway): update disputeHash cal
shalzz
committed