xref gh-14778

As pointed out in the comment by @jamesthomasgriffin, we did not include a pxd file to expose the distribution functions documented in the random c-api. This PR adds a c_distributions.pxd file that exposes them.

Squashed commits:

* BUG: add missing c_distributions.pxd to enable cython use of random C-API

* ENH, TST: add npyrandom library like npymath, test cython use of it

* BUG: actually prefix f-string with f

* MAINT: fixes from review, add _bit_generato_bit_generator.pxd

* STY: fixes from review

* BLD: don't use nprandom library for mtrand legacy build

* TST: WindowsPath cannot be used in subprocess's list2cmdline

* MAINT, API: move _bit_generator to bit_generator

* DOC: add release note about moving bit_generator

* DOC, MAINT: fixes from review

* MAINT: redo dtype determination from review

Fixes this compiler warning:

gcc: numpy/random/bit_generator.c
numpy/random/bit_generator.c:4889:41: warning: comparison of integers of different signs: 'int' and 'uint32_t' (aka 'unsigned int') [-Wsign-compare]
  __pyx_t_6 = ((__pyx_v_self->pool_size != __pyx_v_5numpy_6random_13bit_generator_DEFAULT_POOL_SIZE) != 0);
                ~~~~~~~~~~~~~~~~~~~~~~~ ^  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated

* ENH: Rename seed_seq argument to seed and replace Generator() with default_gen()