add(mining): Restore internal miner #1914

Job	Run time
Generate crates matrix	10s
Check crates matrix	2s
Build zebrad crate	26m 26s
Build zebra-utils crate	16m 20s
Build zebra-test crate	1m 29s
Build zebra-state crate	21m 26s
Build zebra-script crate	3m 23s
Build zebra-rpc crate	20m 8s
Build zebra-node-services crate	3m 35s
Build zebra-network crate	5m 14s
Build zebra-grpc crate	5m 9s
Build zebra-consensus crate	1s
Build zebra-chain crate	1s
Build tower-fallback crate	1s
Build tower-batch-control crate	1s
Open or update issues for building crates individually failures	0s
	1h 43m 26s

Provide feedback