Constants in store_in

[abeakkas]

There is no store_in equivalent of:
A.set_access("[offset]->{A[i]->buf_A[i + offset]}");
where offset is a tiramisu::constant. The following statement:
A.store_in(buf_A, {i + offset})
generates ISL syntax {A[i]->buf_A[i + offset]} which gives error since offset is not defined. We need a way to infer or pass the initial part ([offset]->) to the map.