Enhance PlatformHelper class with a Platform enum property

[BernhardPollerspoeck]

What would you like to be added:

I want to add a Enum to PlatformHelper that indicates the current platform:

public enum EPlatform
{
Undefined,

Wpf,
Wasm,
Linux,
Ios,
Android,

}

In my own Implementation i at the moment set the 1 time setable property in the Program.cs(or compareable). This may should be moved to another location that is not dependant on the template.(There i might need some guidance)

Why is this needed:

To be able to clearly identify the current platform

For which Platform:

• [ x] iOS
• [ x] Android
• [ x] WebAssembly
• WebAssembly renders for Xamarin.Forms
• [ x] Windows
• Build tasks

Anything else we need to know?

I would do the implementation and prepase a PR.

[Youssef1313]

This is a duplicate of unoplatform/uno#11545.

I'll close as a duplicate, but I'm curious though about your exact use case.

[BernhardPollerspoeck]

@Youssef1313 for me its as first usecase deciding navigation and displaying different pages based on platform.

i am going ahead and look into the linked issue and work out my questions there.