feat(common): identify bytes and string slots using storageLayout

[yash-atreya]

Motivation

towards #3869

Solution

• Identify bytes and string with "encoding": "bytes" in storage layout
• The value in the base_slot slot of a bytes/string variable give it's range. See: https://docs.soliditylang.org/en/latest/internals/layout_in_storage.html#bytes-and-string
• Using this length, we can determine the storage range for the data and decode it

Example JSON output

   "stateDiff": {
      "0x0000000000000000000000000000000000000000000000000000000000000001": {
        "previousValue": "0x0000000000000000000000000000000000000000000000000000000000000000",
        "newValue": "0x00000000000000000000000000000000000000000000000000000000000000c7",
        "label": "longString",
        "type": "string",
        "offset": 0,
        "slot": "1",
        "members": [
          {
            "label": "longString[0]",
            "type": "string",
            "offset": 0,
            "slot": "80084422859880547211683076133703299733277748156566366325829078699459944778998"
          },
          {
            "label": "longString[1]",
            "type": "string",
            "offset": 0,
            "slot": "80084422859880547211683076133703299733277748156566366325829078699459944778999"
          },
          {
            "label": "longString[2]",
            "type": "string",
            "offset": 0,
            "slot": "80084422859880547211683076133703299733277748156566366325829078699459944779000"
          },
          {
            "label": "longString[3]",
            "type": "string",
            "offset": 0,
            "slot": "80084422859880547211683076133703299733277748156566366325829078699459944779001"
          }
        ],
        "decoded": {
          "previousValue": "",
          "newValue": "This is a very long string that exceeds 32 bytes and will be stored differently in Solidity storage"
        }
      },
      "0xb10e2d527612073b26eecdfd717e6a320cf44b4afac2b0732d9fcbe2b7fa0cf6": {
        "previousValue": "0x0000000000000000000000000000000000000000000000000000000000000000",
        "newValue": "0x5468697320697320612076657279206c6f6e6720737472696e67207468617420",
        "label": "longString[0]",
        "type": "string",
        "offset": 0,
        "slot": "80084422859880547211683076133703299733277748156566366325829078699459944778998",
        "decoded": {
          "previousValue": "0x0000000000000000000000000000000000000000000000000000000000000000",
          "newValue": "0x5468697320697320612076657279206c6f6e6720737472696e67207468617420"
        }
      },
      "0xb10e2d527612073b26eecdfd717e6a320cf44b4afac2b0732d9fcbe2b7fa0cf7": {
        "previousValue": "0x0000000000000000000000000000000000000000000000000000000000000000",
        "newValue": "0x6578636565647320333220627974657320616e642077696c6c2062652073746f",
        "label": "longString[1]",
        "type": "string",
        "offset": 0,
        "slot": "80084422859880547211683076133703299733277748156566366325829078699459944778999",
        "decoded": {
          "previousValue": "0x0000000000000000000000000000000000000000000000000000000000000000",
          "newValue": "0x6578636565647320333220627974657320616e642077696c6c2062652073746f"
        }
      },
      "0xb10e2d527612073b26eecdfd717e6a320cf44b4afac2b0732d9fcbe2b7fa0cf8": {
        "previousValue": "0x0000000000000000000000000000000000000000000000000000000000000000",
        "newValue": "0x72656420646966666572656e746c7920696e20536f6c69646974792073746f72",
        "label": "longString[2]",
        "type": "string",
        "offset": 0,
        "slot": "80084422859880547211683076133703299733277748156566366325829078699459944779000",
        "decoded": {
          "previousValue": "0x0000000000000000000000000000000000000000000000000000000000000000",
          "newValue": "0x72656420646966666572656e746c7920696e20536f6c69646974792073746f72"
        }
      },
      "0xb10e2d527612073b26eecdfd717e6a320cf44b4afac2b0732d9fcbe2b7fa0cf9": {
        "previousValue": "0x0000000000000000000000000000000000000000000000000000000000000000",
        "newValue": "0x6167650000000000000000000000000000000000000000000000000000000000",
        "label": "longString[3]",
        "type": "string",
        "offset": 0,
        "slot": "80084422859880547211683076133703299733277748156566366325829078699459944779001",
        "decoded": {
          "previousValue": "0x0000000000000000000000000000000000000000000000000000000000000000",
          "newValue": "0x6167650000000000000000000000000000000000000000000000000000000000"
        }
      }
    }

PR Checklist

• Added Tests
• Added Documentation
• Breaking changes

[grandizzy]

looks good, left some comments / nits, pls check

[grandizzy]

lgtm!