Feat/offline election prediction tool #1407

Job	Run time
set-image	4s
Run tests	3m 48s
Check documentation	1m 47s
Clippy	3m 13s
Build polkadot-staking-miner binary	3m 58s
Check formatting	51s
Check code	2m 30s
Test Docker image build	31s
Build and publish Docker image	0s
	16m 42s

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