[#2] [Android] Update app to follow Android Compose template structure

[luongvo]

• Close #2

What happened 👀

• Update the KMM project for Android following the Android Compose template.
• Stop using BuildConfig from Gradle 8.
• Add signingConfigs for debug and release builds.

Insight 📝

• I followed a good approach to managing Dependencies & Versions from this KMM's sample project PeopleInSpace.
• Gradle does not generate BuildConfig by default. We should stop using and follow the best practices to have custom code in each build source folder. https://developer.android.com/build/releases/past-releases/agp-8-0-0-release-notes#default-changes

Proof Of Work 📹

Apps should work properly, with no changes in UI.

[luongvo]

@phongvhd93 👋