On "expected X found Y" type errors, highlight the actual difference

[amishne]

e.g.

expected { i32, i32, i32, i32, i32 }, found { i32, i32, i31, i32, i32}

Will become

expected { i32, i32, i32, i32, i32 }, found { i32, i32, i31, i32, i32}