feat: upgrade testing framework

[nickolas-dimitrakas]

Background

The SDK was using an older custom testing framework that required manual setup and didn't integrate well with modern development workflows. This migration to Rooibos (the standard Roku testing framework) provides better developer experience with automated test detection, VSCode integration, and cleaner test syntax.

What Has Changed

• Migrated from custom test framework to Rooibos 5+ with BrighterScript
• Converted all test files to modern BrighterScript syntax (.spec.bs)
• Added VSCode debug configurations for one-click test execution
• Updated Main.bs to auto-detect test vs production builds
• Created run-tests.sh script for command-line test execution
• Updated build configurations (bsconfig.json, bsconfig-test.json)
• Refreshed documentation with setup and testing instructions

Checklist

• I have performed a self-review of my own code.
• I have made corresponding changes to the documentation.
• I have added tests that prove my fix is effective or that my feature works.
• I have tested this locally.

Additional Notes

• This PR is branched off refactor: remove legacy example app #46 and needs to be rebased

Reference Issue (For employees only. Ignore if you are an outside contributor)

• Closes https://rokt.atlassian.net/browse/SDKE-745

[jamesnrokt]

Approved pending changing the base branch and merging of #44