Implement native code helper to generate a new Guid

[nfbot]

From nf-interpreter created by josesimoes : nanoframework/nf-interpreter#323

From nanoframework/nf-class-libraries#40

This is GenerateNewGuid___STATIC__SZARRAY_U1.

The method should return an array with 16 random byte, ready to generate a valid Guid.

[networkfusion]

Is this also done for stm32 devices? I saw no mention of it in the PR?

[josesimoes]

Is this also done for stm32 devices? I saw no mention of it in the PR?

Yes it is.

Granted, the mention to ESP32 in the PR comment is probably misleading... 😅 What was added in the PR was the code to generate the GUID AND the random generator implementation for ESP32 (which was missing until now). 😜