Without the project files, certain settings will not be saved by this
python call. This defaults to false (current behavior) but setting the
`aSkipSettings` to true will revert to v5 behavior
Fixes https://gitlab.com/kicad/code/kicad/issues/11323
KiCad cannot have more than one board/project open, so disallow
the Python APIs for loading additional boards when the frame is
present. Inherit the SETTINGS_MANAGER from the frame when present
instead of creating a new one that won't have the loaded project.
Currently there is pcbnew.ExportSpecctraDSN() but it needs a pcbnew
frame set which makes it unusable outside of the scripting window or a
plugin.
This refactors actual exporting logic into separate helper and adds an
overload to ExportSpecctraDSN(board, filename) that doesn't need pcbnew
window.