Upgrade the bridge to work with chain signatures #616

Job	Run time
Test bridge-token-factory	2m 25s
Test erc20-bridge-token	56s
Test erc20-connector	1m 51s
Build and diff erc20-connector	2m 10s
Build and diff erc20-bridge-token	1m 5s
Test silo-to-silo	5m 22s
Test token-locker	3m 34s
Build and diff bridge-token	3m 29s
Build and diff bridge-token-factory	3m 43s
Build and diff token-locker	3m 41s
	28m 16s

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