[UPM] Package embedded structure

UPM embedded project structure for testing and play sample scenes.

Additionally, were did some refactorings and new implementations (specially for Android and WebGL )

[VSCode]

• Migrate to use the new extension "visualstudiotoolsforunity.vstuc"
• Added a default Unity editor debug configuration to .vscode/launch.json

[WebGL]

• Refactoring to a more "vanilla" Javascript approach using a Vibration singleton class
• Added IsVibrateSupported() method to main .jslib
• Added repeat parameter to VibrateWithPattern() method on main .jslib
• Added a package.json file to the root embedded Unity project, to run and test WebGL builds

[Android]

• Added a generic static C# class for AndroidBuild to get Android API level

[Unity/C#]

• Refactorings to better accomplish the scene example script VibrationExample.cs
• Added Editor unit tests in order to test MobileTimeUnit.cs class
• Refactoring on Samples/VibrationExample to consider use WebGL implementations as well