Implement Rewards API

[mehmetegemen]

Description

Implement reward module API in api.ts for getBlockReward function and implement this API to reward module class as specified in https://research.lisk.com/t/define-state-transitions-of-reward-module/316#getblockreward-13

getBlockReward(blockHeader):
    if isValidSeedReveal(blockHeader.generatorAddress, blockHeader.seedReveal) == false:
        return 0

    defaultReward = getDefaultRewardAtHeight(blockHeader.height)
    if impliesMaximalPrevotes(blockHeader) == false: 
        return defaultReward / REWARD_REDUCTION_FACTOR_BFT

    return defaultReward

Acceptance Criteria

• getBlockReward function must be implemented and unit tested

Related Issue

#6686

[mehmetegemen]

Suspended until assets will be part of the context since we need seedReveal from the assets.