Add -cwd option to change working directory when app starts

[AKuHAK]

Added -cwd option for those cases when neutrino at start has no access to cwd. This also require to move system.toml parser after argument parser, so now system.toml is stronger then arguments

[rickgaiser]

A fallback path is a workaround for broken loaders. It will also make neutrino less deterministic.

Perhaps a parameter can be added to neutrino to choose another CWD? Like -cwd=mc0:/neutrino/. In that case the user is always in control of what config is used from what location.

[AKuHAK]

@rickgaiser this will require more changes, as argument parser should be moved before toml parser in that case, thus making arguments stronger than cfg. Also no need for additional argument, we can chdir if -cfg option is present and if not present load from default cwd. The only downside you will loose 2 toml files simultaneous support (system + user-defined combination). Or it is possible to load system driver (from ./) after user cfg regardless if user cfg was successfully loaded or not.

[AKuHAK]

@rickgaiser pr is ready for review

[rickgaiser]

Lgtm, if you change the 1 typo then I will merge.

[AKuHAK]

done