feat: exit with error status on compilation failure

[mhasel]

When the compilation ends with a diagnostic with severity Error, we now no longer exit with 0 (Success) but rather 1 (Catchall for general errors, as defined in the Linux Documentation Project). I've also looked at the BSD standards (mirrored in the exitcode crate) and, if we want to follow these guidelines, we could opt to change it to 65 - Data Error, but I would suggest to stick with 1 for now until we decide on a more fine-grained exit approach for different error scenarios.

Refs: #817

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 5 lines in your changes are missing coverage. Please review.

Project coverage is 95.63%. Comparing base (dafaa7e) to head (9c4eb39).

Files	Patch %	Lines
compiler/plc_driver/src/main.rs	0.00%	5 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1183 +/- ## ========================================== - Coverage 95.64% 95.63% -0.01% ========================================== Files 148 148 Lines 43604 43607 +3 ========================================== Hits 41703 41703 - Misses 1901 1904 +3 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.