Stateful Statediff: Implement Compressors' combination

[kpp]

We need this feature to merge two diffs into one. Before we implemented it like this:

pub fn merge_state_diffs(old_diff: StateDiff, new_diff: StateDiff) -> StateDiff {
    let mut new_diff_map = HashMap::<Vec<u8>, Option<Vec<u8>>>::from_iter(old_diff);

    new_diff_map.extend(new_diff);
    new_diff_map.into_iter().collect()
}

But now because of #1505 we have to implement the binary operation with multiple identities for Compressors:

For U256:

x + Add(0) = x
x + Sub(0) = x
Add(0) + x = x
Sub(0) + x = x

Transform(0) + x = x

_ + Transform(x) = Transform(x)
_ + NoCompression(x) = NoCompression(x)

Transform(x) + Sub/Add(y) = Compress(x+-y)
NoCompression(x) + Sub/Add(y) = Compress(x+-y)

Add(x) + Add(y) = Add(x + y) // handle overflow
Sub(x) + Sub(y) = Sub(x + y) // handle overflow
Add(x) + Sub(y) = Add(x - y) // handle overflow
Sub(x) + Add(y) = Sub(x - y) // handle overflow

Unfortunately for Add/Sub + Add/Sub we lose information of the original operands (lhs, rhs), so the result of combination of Add/Sub + Add/Sub may be suboptional in terms of diff size, because Compress(x, y) + Compress(a, b) may result in Transform too, not only in Add/Sub =(

TODO: implement combination for AddInlined: #1520

With #1511:

For code_hash B256:

x + Same = x
Same + x = x

_ + Removed = Removed
Removed + x = x

_ + Set(x) = Set(x)

Belongs to #1237