Support for transaction read/write sets

[peterjgilbert]

Needed in order to support confidential to non-confidential cross-contract/service calls Initially, read/write sets will be specified at per-contract granularity.

Details

• Read/write set encoding and transport
• Transaction scheduler should use CheckTx
• Support special atomic storage operations on keys
• Runtime should verify read/write sets
• Read/write set-aware transaction scheduler algorithm
• Replicated transaction scheduling and discrepancy detection
• Committee scheduler should schedule parallel compute committees

Estimated cost: 13d+

[kostko]

Filed subissues.

[kostko]

Updated dependencies as some issues were not covered initially but need to be done first (#1963 and #1466) in order to do reverts safely.