[Phase 5] Run BrowserStack Maestro from E2E matrix rows

[kieran-osgood-shopify]

Stack Context

This is Phase 5 of the BrowserStack Maestro E2E stack for Checkout Kit, stacked on the RN iOS artifact workflow.

Parent issue: https://github.com/shop/issues-checkout-kit/issues/1099
Epic: https://github.com/shop/issues-checkout-kit/issues/1084

What?

Previous PR's setup a CLI that expands the matrix.yml into json in browserstack format
This PR uploads that json, as well as the zip of the test suite, to browserstack
At this point we still aren't going to see any tests running on PR's because they're enabled as a CI trigger in #364

• uploads app artifacts and Maestro suite zip to BrowserStack
• wires the Bitrise run workflow to call the BrowserStack runner

[kieran-osgood-shopify]

• [Phase 7] Soft-launch E2E PR checks #364 : 2 dependent PRs (#401 , #417 )
• [Phase 6] Report E2E results to GitHub #363
• [Phase 5] Run BrowserStack Maestro from E2E matrix rows #362 👈 (View in Graphite)
• [Phase 4] Build React Native iOS E2E IPA artifact #361
• [Phase 3] Build React Native Android E2E APK artifact #360
• [Phase 2] Add Bitrise E2E pipeline skeleton #357
• [Phase1] Add E2E matrix launch smoke foundation #356
• main

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[kieran-osgood-shopify]

These will be coming in to play with another PR I am preparing to give us a way to trigger runs for specific devices and OS's (e.g. iOS 27 Beta)