RSKIP-240: Implement Storage Rent in RSK

This proposal introduces a simpler design, while sharing a common philosophy and objectives of earlier proposals and the RSK white paper.

The proposal introduces rent as variable fees for accessing state trie. These fees can help

  • make storage payments fairer by introducing a time dimension to storage fees
  • improve state caching by introducing a cache hierarchy
  • help secure the network from some IO attacks
  • reduce the likelihood of storage spam and gas arbitrage
  • encourage developers and product designers to treat state storage more judiciously - important for long term scalability, sustainability and fairness

Link to proposal (RSKIP240)