Add custom_wdio_E2E tests for Android and iOS using WebdriverIO + Appium

[parth-bstack]

This PR introduces a new folder named custom_wdio_E2E/ that contains separate end-to-end test setups for Android and iOS using WebdriverIO + Cucumber + Appium. It includes:

• Android and iOS specific folders
• Sample feature files for search and input validation
• Step definitions
• BrowserStack configs for public, local, and parallel test runs
• No changes made to the existing setup or files

Tested and verified locally. Ready for review and integration.

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