Add diagnostics in the preprocessor

[alessio-perugini]

Describe the request

Add diagnostics support in the preprocessing.
In #2182 we implemented the support of diagnostics in the compilation phase.
The parser should be able to handle the output coming from the processor as GCC backs it.

Describe the current behavior

Currently, we support the new diagnostics field only when something bad happens in the compilation.

Arduino CLI version

main

Operating system

Linux

Operating system version

Ubuntu 23.04

Additional context

As an example, we should see diagnostics if we use this sketch:

#ouch!
void setup() {}
void loop() {}

Issue checklist

• I searched for previous requests in the issue tracker
• I verified the feature was still missing when using the nightly build
• My request contains all necessary details