`--preprocess` key prints informational messages to the output

[okalachev]

Describe the problem

When it's needed to get the preprocessed C++ code of a sketch, one can use the --preprocess key (Print preprocessed code to stdout instead of compiling) and redirect the output to a file.

This key works well, but in the end of the output it prints the list of cores and libraries used, like this:

Used platform Version Path                                                             
esp32:esp32   2.0.7   /Users/user/Library/Arduino15/packages/esp32/hardware/esp32/2.0.7

If it would be printed to stderr, it would be OK, but since it's in the stdout, it appears in the resulting file, thereby breaking it.

To reproduce

Compile a sketch with --preprocess key.

Expected behavior

The list of used cores and libraries should be disabled when using --preprocess key, or be printed to stderr (more preferable).

Arduino CLI version

0.31.0

Operating system

macOS

Operating system version

macOS 13.3

Additional context

No response

Issue checklist

• I searched for previous reports in the issue tracker
• I verified the problem still occurs when using the nightly build
• My report contains all necessary details