* feat(slot-reservations): Support reserving slots
Closes#898.
Wire up reserveSlot and canReserveSlot contract calls, but don't call them
* Remove return value from `reserveSlot`
* convert EthersError to MarketError
* Move convertEthersError to reserveSlot
* bump codex-contracts-eth after rebase
* change `canReserveSlot` and `reserveSlot` parameters
Parameters for `canReserveSlot` and `reserveSlot` were changed from `SlotId` to `RequestId` and `UInt256 slotIndex`.
* bump codex-contracts-eth after rebase
* bump codex-contracts-eth to master after codex-contracts-eth/pull/177 merged