feat: permissionless fees claiming #89
Description
The protocol fees can currently only be withdrawn by the program update authority. Moreover, fees are always received by the program update authority. This poses a problem for automatically distributing protocol fees in the context of the staking program.
Storing a fees receiver in the Program Config would enable anyone to claim protocol fees by ensuring they are sent to the selected fees receiver. Allowing the fee receiver to change would make the system adaptable to future changes.
The alternative would be to simply allow the admin to send the fee to a configurable address, but that would prevent permissionlessness.