Implicit type conversions in header files

[trampas]

When changing my compiler flags to include -Wconversion many of the zephyr headers are flawed as having questionable type conversions. This include atomic.h as well a several other headers.

I have not found a good way to work around this problem. If I fix the headers locally they will not propagate to next clean build. I can try disabling warnings in source code but have to do that for every include from zephyr, which is not clean or easy.

I could do a fix for headers pull request but we are locked into older zephyr version. Additionally there is risk I would create more bugs than I fix in the process or mask bugs.

It is kind of a shame on zephyr not to require no implicit type conversions on the project, as these conversations are often laten bugs.

[github-actions]

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[nashif]

This duplicates #72488