Introduce randomized leader election

Randomized leader election has been being implemented in the branch https://github.com/CodeChain-io/codechain/tree/VRF-election. Let's adopt the change in foundry repository.

Start by reviewing the VRF-election branch linked in the issue and compare its randomized leader-election implementation with the foundry repository. Determine the integration points and dependencies needed to adopt the change. Done means the branch's leader-election work is incorporated into foundry and the repository uses the randomized behavior.

Vom Indexierungsmodell aus dem Issue-Text verfasst.