custom unstake algo

[0xripleys]

Allow each hook to define a custom unstaking algorithm. This way, different LSTs can have different unstaking behaviour.

Note that unstaking via liquid_staking::redeem will still work, however the admin can set different fees on the two unstaking flows to incentivize what they want.

Default unstaking flow (which still works!):

let sui = liquid_staking::redeem(&mut system_stat, liquid_staking_info, lst, scenario.ctx());

New custom unstaking flow

let custom_redeem_request = lst_info.custom_redeem_request(lst_to_unstake,&mut system_state, scenario.ctx());
weight_hook.handle_custom_redeem_request(&mut system_state, &mut lst_info, &custom_redeem_request, scenario.ctx());
let sui = lst_info.custom_redeem(custom_redeem_request, &mut system_state, scenario.ctx());