Feat/offline election prediction tool #1476

Job	Run time
set-image	3s
Clippy	5m 43s
Run tests	5m 25s
Build polkadot-staking-miner binary	5m 34s
Check documentation	3m 57s
Check code	4m 43s
Check formatting	57s
Test Docker image build	29s
Build and publish Docker image	0s
	26m 51s

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