reward: SupplyManager correctly handles block rewinds

[blukat29]

Proposed changes

• The GetTotalSupply API had a bug that over-accumulates TotalMinted and TotalBurnt after a manual block rewinding via debug_setHead. See https://app.circleci.com/pipelines/github/kaiachain/kaia/355/workflows/a330fe31-08f5-4771-bd3a-3459d4849a70/jobs/1776 and reward/supply_manager_test.go:TestCatchupRewind for the test reproducing it.

1. SupplyManager catchup thread is guarded against out-of-order ChainHeadEvent that might be emitted after block rewind (i.e. debug_setHead)
2. Block rewind (i.e. BlockChain.setHeadBeyondRoot) involves deletion of SupplyCheckpoints, and restarting the catchup thread.
3. Invalidate existing supply checkpoints (dubbed "accRewards"), triggers every node upgrading to v1.0.2 re-accumulate from the genesis. Because of the bug, nodes v1.0.1 or earlier which undergone setHead at least once might have corrupt accRewards data.

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[blukat29]

Fixed api_backend_test unit test and linter.