Switch the distributed transaction commit protocol to the RPC protocol

SERVER-37364 Allow transactions that use two-phase commit to respect lower writeConcern than majority

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• Open

SERVER-36640 Add way for TransactionCoordinator to signal when the commit decision is made and persisted

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• Closed

SERVER-36854 Change TransactionCoordinator state machine to allow for persisting decision

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• Closed

SERVER-36860 Implement functions for persisting/deleting/reading coordinator commit decisions

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• Closed

SERVER-37165 Implement logic to persist/delete commit document for TransactionCoordinator

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• Closed