Use Variable Size Indices in Sparse Qlinear Code (#85247)
Final changes to enable sparse weight packing with variable size indices
pack_block_sparse.cc is deleted because all functions in it have a template added, so they are moved to pack_block_sparse.h
Differential Revision: [D39025651](https://our.internmc.facebook.com/intern/diff/D39025651/)
**NOTE FOR REVIEWERS**: This PR has internal Meta-specific changes or comments, please review them on [Phabricator](https://our.internmc.facebook.com/intern/diff/D39025651/)!
Pull Request resolved: https://github.com/pytorch/pytorch/pull/85247
Approved by: https://github.com/digantdesai
