bonding: Skip fee calculation for voting power

[victorges]

What does this pull request do? Explain your changes. (required) This fixes a bug observed after deploying the new BondingVotes to production.

It happens when trying to calculate voting power for a delegator whose transcoder hadn't initialized their cumulativeFeeFactor on the corresponding round.

This causes the voting power calculation to underflow, because we don't initialize the cumulativeFeeFactor of the endPool like BondingManager does. Even though we don't really care about fees for voting power, the underflow causes a revert on any transaction that needs to access the delegator votes at the uninitialized round.

Specific updates (required)

• Break delegatorCumulativeStakeAndFees logic in 2, to allow calculating only stake or only fees
• Call the stake-only version from BondingVotes
• PENDING: a couple tests

How did you test each of these updates (required) yarn test that it didnt change any existing behavior on BondingManager New tests on BondingVotes May do a tenderly fork test before actual deploy

Does this pull request close any open issues? N/A

Checklist:

• [ ] README and other documentation updated
• [x] All tests using yarn test pass

[coveralls]

Pull Request Test Coverage Report for Build 6513140765

• 8 of 8 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.07%) to 99.587%

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Totals
Change from base Build 6497587953:	0.07%
Covered Lines:	1010
Relevant Lines:	1013

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💛 - Coveralls

[victorges]

@yondonfu added tests to the EarningsPoolLIP36 new funcs! Getting 100% coverage on those now