fix: Add old names to platform for compatibility

[NathanaelA]

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What is the current behavior?

We somehow renamed Platform.screen & Platform.device to Platform.Screen and Platform.Device in the Mono-Repo transition. This breaks plugins and applications, including all versions of NS-Theme's 2.x. This also breaks all examples and the current documentation.

What is the new behavior?

Adds a simple compatibility classes so that Platform.screen and Platform.device both point to the upper case version, to allow every plugin and use of this to work. The new name Platform.Screen and Platform.Device still work as we are using them in other places...

[rigor789]

Looks fine to me, just missing the change in the definitions (index.d.ts)

[farfromrefug]

Really good idéal to bring this back !

[rigor789]

@NathanaelA could you make the same change in the index.d.ts file?