Factor out common dialog code from global symbol library table dialog for
loading initial library table.
Update global symbol library table code to user factored out common dialog
code.
wxWidgets provides a system-dependent string for "*" or "*.*" depending
on the system. Unfortunately, wxFormBuilder does not use this and
instead defaults to the Windows-only "*.*". This is an ugly work
around.
Fixes: lp:1810221
* https://bugs.launchpad.net/kicad/+bug/1810221
Create a dialog to give the user options to configure the global symbol
library table the first time Eeschema is run when no global symbol library
table exists.