[DRAFT] More rewrites for array/map clash

[msooseth]

Description

More rewrites so we don't give up in case of map vs array in readStorage, but know that they cannot clash. Here is how we know they cannot clash:

• Maps and Arrays hash a different SIZE input: 64B vs 32B. Hence, you'd need a collision of Keccak for them to collide
• HOWEVER, when there is an offset, then the offset could be set by the attacker to be keccak(a)-keccak(b). So when an offset is allowed, it must be limited. We limited the offset to 256 is other places:

      -- Finding two Keccaks that are < 256 away from each other should be VERY hard
      -- This simplification allows us to deal with maps of structs
      (Add (Lit a2) (Keccak _), Add (Lit b2) (Keccak _)) | a2 /= b2, abs (a2-b2) < 256 -> go slot prev
      (Add (Lit a2) (Keccak _), (Keccak _)) | a2 > 0, a2 < 256 -> go slot prev
      ((Keccak _), Add (Lit b2) (Keccak _)) | b2 > 0, b2 < 256 -> go slot prev

so I'm limiting it here to the same offset. Which means it's impossible to find a collision that are within 256 of each other. This is accepted to be impossible.

Checklist

• tested locally
• added automated tests
• updated the docs
• updated the changelog

[blishko]

Are we sure we want to do these rewrites?