[Attributor] Deduce dereferenceable based on accessed bytes map

Summary:
This patch introduces the deduction based on load/store instructions whose pointer operand is a non-inbounds GEP instruction.
For example if we have,
```
void f(int *u){
 u[0] = 0;
 u[1] = 1;
 u[2] = 2;
}
```
then u must be dereferenceable(12).

This patch is inspired by D64258

Reviewers: jdoerfert, spatel, hfinkel, RKSimon, sstefan1, xbolva00, dtemirbulatov

Reviewed By: jdoerfert

Subscribers: jfb, lebedev.ri, xbolva00, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D70714