Propose Validator Exit

Initiate a validator exit proposal which, if accepted results in the full withdrawal of a set of validators. Only the beneficiary in the exit proposal can withdraw the validator balance. Each Proposal has a unique identifier - proposalId.

Method: proposeExit(proposal)

Arguments: proposal (struct) – Contains validator index, deadline, and beneficiary details.

Permissions: OPERATOR_ROLE

Events: when called, the method emits a Proposalevent.