Pass that turns symbol assignment to dynamic map ranges

In many cases we generate SDFGs with symbol assignments where they could be dynamic map ranges.

Example:
```python
@dace.program
def spmv(A_row: dace.uint32[H + 1], A_col: dace.uint32[nnz], A_val: dace.float32[nnz], x: dace.float32[W]):
b = np.zeros([H], dtype=np.float32)

for i in dace.map[0:H]:
begin = A_row[i]
end = A_row[i + 1]
for j in dace.map[begin:end]:
b[i] += A_val[j] * x[A_col[j]]

return b
```

We should make a pass or transformation to "demote" certain symbol assignments to the tasklets or maps as necessary.