docs: add TestingBot cloud provider page

[gmegidish]

Adds docs/src/cloud-providers/testingbot.md documenting the TestingBot @testingbot/mobilewright-driver integration, based on https://testingbot.com/support/app-automate/mobilewright — install, credentials, driver config with per-platform apps, device selection, driver options, runtime commands, and local↔cloud driver switching. Linked from the Cloud Providers overview.

Test plan

• Docs site builds and the TestingBot page renders in the Cloud Providers sidebar
• Verify the TestingBot account-settings link is correct

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Essentials

Run ID: 3f3949e5-2d04-4aec-9b88-b128ab0c3fb3

📥 Commits

Reviewing files that changed from the base of the PR and between 512ae86 and 4a94f2a.

📒 Files selected for processing (2)

• docs/src/cloud-providers/index.md
• docs/src/cloud-providers/testingbot.md

Cache: Disabled due to data retention organization setting

Knowledge base: Disabled due to data retention organization setting

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Walkthrough

Adds TestingBot to the supported cloud provider index. Adds a dedicated guide for installation, credentials, device selection, app uploads, driver options, test execution, runtime commands, local-driver selection, and documentation links.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch docs/testingbot-cloud-provider

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_{Comment @coderabbitai help to get the list of available commands.}