[Gradle Tutorials] Add VS Code section to main Gradle guide

[JadeCheah]

Fixes #182

Summary

• Added vscode–specific instructions (reload steps, Scenario 2 guide, and running Gradle tasks) in main Gradle guide for consistency.

Clarification

• I initially thought of removing the extra sections on running tasks, testing, and editing build files in vscImportingGradleProject.md to keep it more focused on "importing", and move the usage content to the main Gradle guide. But I realized they are quite specific to VS Code and its Gradle extension rather than general Gradle usage.
• Is it okay to leave the VS Code Gradle content as it is for now?