Sparse CSR CPU: add `triangular_solve_out` (#62180)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/62180
This PR adds CPU dispatch for `triangular_solve` with sparse CSR matrix.
The implementation uses MKL Sparse library. If it's not available then a runtime error is thrown.
cc nikitaved pearu cpuhrsch IvanYashchuk
Test Plan: Imported from OSS
Reviewed By: pbelevich
Differential Revision: D32581395
Pulled By: cpuhrsch
fbshipit-source-id: 41c7133a0d2754ef60b5a7f1d14aa0bf7680a844
