Encodes DelegationManager.queueWithdrawals([{strategies, depositShares, withdrawer}]).
Queues a withdrawal for the specified strategies and share amounts. Shares enter a ~14-day escrow.
After escrow, use POST /transactions/prepare/complete-withdrawal to complete all eligible withdrawals in one batch.

The request body expects a shares array (not sharesGwei). Values must match the unit returned by the stakes endpoint's shares field.

Nonce handling: The nonce is computed at call time. If you prepare multiple transactions before broadcasting, they will share the same nonce and only the first will succeed. Broadcast and confirm each transaction before preparing the next.