[sparse] Add padding for dense matrices in semi-structured sparse (#110583)
Summary:
Currently we have shape constraints in semi-structured sparsity for both
CUTLASS and cuSPARSELt
These shape constraints unfortunately apply to both the dense and sparse
matrices in sparsedense matmul.
This PR adds in support for calling `F.pad` in order to pad dense
matrices to the right size with zeros and then pull out the
corresponding rows from the resultant result matrix.
We also throw a warning in this case.
The tests have also been updated to take in a dense_input_shape
parameter.
Test Plan:
```
python test/test_sparse_semi_structured.py
```
Reviewers:
Subscribers:
Tasks:
Tags:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/110583
Approved by: https://github.com/alexsamardzic, https://github.com/cpuhrsch
