test: add tests to blas/ext/base/dnannsumbn2#3205

Planeshifter merged 2 commits intostdlib-js:developstdlib-js/stdlib:developfrom

saurabhraghuvanshii:dnannsumkbn2-testsaurabhraghuvanshii/stdlib-gs:dnannsumkbn2-testCopy head branch name to clipboard