[RFC]: add accessor array support to `blas/base/gasum`

[kgryte]

Time estimate without AI: 1hr
Time estimate with AI: 45mins

[headlessNode]

PR: stdlib-js/stdlib#5439
Time till PR: 34 mins
AI Model: Claude 3.5 Sonnet
Loom Recording: Link

[headlessNode]

Notes:

• I used Cursor's @Git feature for this issue, with which we can index a relevant commit for reference. It worked really well the main logic was complete in 15 mins with having to add minor tweaks.

• AI did hallucinate a bit with tests. So rest of the time was spent on optimizing tests.

• AI also missed a test-case, which when I added after PR creation, revealed a small bug in the implementation.

[headlessNode]

Post Review Notes:

• 4 additional minutes spent on fixing a bug, adding a test case for 100% coverage and refactoring documentation.