Fix default startup directory

[LabhanshAgrawal]

Fixes #4197

The bug was introduced in #3769 , which probably went unnoticed because on mac and linux default config dir is home.

[ppot]

Honestly, can you rework this workingDirectory thing ? I know you where not the one who made the original, but homeDirectory was change for cfgDirg and also, this should be a plugin thing.
Also, this should be a profileDirectory but since mostly not everyone will use it, it's just noice.

The comment // set custom startup directory (must be an absolute path) should say instead
// set profile directory for default startup (must be an absolute path)

[Stanzilla]

Could be done in a follow up PR, imo. Merging this now to get the fix in

[LabhanshAgrawal]

@ppot can you elaborate a bit, not sure if I understand your comment fully.