Add @stevenckngaa as a code owner

[jingtang10]

IMPORTANT: All PRs must be linked to an issue (except for extremely trivial and straightforward changes).

Fixes NA

Description
Add @stevenckngaa as a code owner

Alternative(s) considered
NA

Type
Choose one: Other

Screenshots (if applicable)

Checklist

• I have read and acknowledged the Code of conduct
• I have read How to Contribute
• I have read the Developer's guide
• I have signed the Google Individual CLA, or I am covered by my company's Corporate CLA
• I have discussed my proposed solution with code owners in the linked issue(s) and we have agreed upon the general approach
• I have run ./gradlew spotlessApply and ./gradlew spotlessCheck to check my code follows the style guide of this project
• I have run ./gradlew check and ./gradlew connectedCheck to test my changes locally
• I have built and run the reference app(s) to verify my change fixes the issue and/or does not break the reference app(s)