[NNC] Fuse loops that have the same bounds as expressions (#55997)
Summary:
This PR allows fusing loops whose bounds are specified as expressions that are equal.
For example:
```
for (int j = 0; j < M + N; j++) {
A[j] = 10 * j;
}
for (int k = 0; k < M + N; k++) {
B[k] = 20 * k;
}
```
`fuseLoops(j, k)` is possible since the stop bounds of the two loops are equal though they are different `Expr*` and will result in:
```
for (int j = 0; j < M + N; j++) {
A[j] = 10 * j;
B[j] = 20 * j;
}
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/55997
Reviewed By: bertmaher
Differential Revision: D27841270
Pulled By: navahgar
fbshipit-source-id: a64e4503b7f8f28bc0c9823225bc923177bb4c2e
