ENH: (Sparse) Support  boolean output from sparsetools binop routines, apply this in sparse boolean comparisons.

This allows the [`csr_binop_csr`](https://github.com/cowlicks/scipy/blob/binop-output/scipy/sparse/sparsetools/csr.h#L839) and [`bsr_binop_bsr`](https://github.com/cowlicks/scipy/blob/binop-output/scipy/sparse/sparsetools/bsr.h#L571) routines to have a boolean output type. This is then used in the `!=`, `==` boolean comparisons.

__This will need to be rebased if my other [PR for inequalities](https://github.com/scipy/scipy/pull/2586) is merged to master first. Or vice versa.__