Fee Manager for `erc-to-native` bridge in POSDAO chain

[akolotov]

As per requirement for the erc-to-native bridge every time when the fee for transferring assets needs to be distributed it is necessary to pass the request to addBridgeNativeFeeReceivers (https://github.com/poanetwork/posdao-contracts/blob/71c742bd2c4f84c8cc9a77bac78a39c5e2d1ae7c/contracts/abstracts/BlockRewardBase.sol#L48) of the block reward contract. This method will schedule the fee distribution among the network validators and stakers.

So, overall logic will as the following:

1. from the foreign chain to the home chain:

   • onExecuteAffirmation should call distributeFeeFromAffirmation that will call addBridgeNativeFeeReceivers. It is not needed to call addBridgeNativeFeeReceivers for every validator.

2. from the home chain to the foreign chain:

   • instead of burning part of the value: https://github.com/poanetwork/poa-bridge-contracts/blob/0f15d7f108647bdc458c96a8a0cc1f51468c0e12/contracts/upgradeable_contracts/erc20_to_native/HomeBridgeErcToNative.sol#L27-L31 entire value must be burnt.
   • onSignaturesCollected should calculate fee value, call distributeFeeFromSignatures. The latter will call addBridgeNativeFeeReceivers to schedule the minting of new coins for the network validators and stakers.

[akolotov]

Available in the release 2.3.0