ConfigFetcher is responsible for github api integration related to the
configuration operations.
Basically checks remote hash of the corresponding chain configuration.
If there is a mismatch between local and remote instance, overrides the
local instance with remote changes for testnet and mainnet configurations.
Check local state of the configuration file in the vault (if they exists)
and compare them to the remote one in github. If a change is detected asks
user if they want to update, and does the update for them.