Updated compiler version detection

This fixes multiple issues/inconsistencies around  `get_compiler_version()`:
* With no shell allocated, launching the compiler could fail even
  with proper paths being set.
* The return value was described as "an array of version numbers as ints",
  but the function actually returned a `Dictionary` (or `None`).
* Not all calls were properly handling a `None` return value in case of errors.
  On Windows this broke compiling for me since #81869 with default settings.
* Some calls defined inconsistent defaults/fallbacks (`0` or `-1`).

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