Slot reservations implementation

[emizzle]

Defined in the slot reservations codex-research PR https://github.com/codex-storage/codex-research/pull/190

Subtasks:

• [ ] Contracts
  • Allow 3(?) slots to be reserved, reserveSlot (returning bool if successful), return true for now stub for canReserveSlot(address, SlotId), return true for now, call from reserveSlot Client
    • Wire up reserveSlot and canReserveSlot contract calls, but don't call them
• [ ] Contracts
  • https://github.com/codex-storage/codex-contracts-eth/issues/115 (add to StorageRequest struct only) Client
  • Support dispersal parameter (API, API spec, StorageRequest object, etc)
• [ ] Client
  • Add SaleReserving state -- SalePreparing -> SaleReserving
  • Refactor slotqueue's seen flags (seen > seenNoAvailability, add seenNotEligible, pause on seenNoAvailability, but don't pause on seenNotEligible)?
• [ ] Contracts
  • Third reservation emits SlotFullyReserved event Client
  • Slot queue listens for SlotFullyReserved and removes slot from queue
• [ ] Contracts
  • Add calculation for expanding window (https://github.com/codex-storage/codex-contracts-eth/issues/116) (use blockhash at time of createStorageRequest for random base SlotID?
• [ ] Contracts
  • Disallow fillSlot if slot was not reserved (return false)

[emizzle]

No longer using this task as a parent task, using the epic https://github.com/codex-storage/codex-pm/issues/45 instead.