Prettier printing for variables

[Xazax-hun]

Would be nice to condense (*a).f into a->f for diagnostics. It should work well for multiple dereferences. So:

(*(*a)).f => (*a)->f

[Xazax-hun]

Another problem:

void f(const T& x) {
  int i;
  return &i; // Here we will say that the expected pset is *x, which is confusing. 
}

[Xazax-hun]

Some improvements were made in https://github.com/mgehre/llvm-project/commit/082790623dde33297cac949e7ca032e2b0595a54