Add config schema for core.restorePreviousWindowsOnStart
Add config schema for core.restorePreviousWindowsOnStart

Additionally updates the description for core.openEmptyEditorOnStart to
match.

bsmr-x-script/atom,PKRoma/atom,ardeshirj/atom,xream/atom,t9md/atom,bsmr-x-script/atom,brettle/atom,AdrianVovk/substance-ide,ardeshirj/atom,xream/atom,kevinrenaers/atom,atom/atom,kevinrenaers/atom,me-benni/atom,sotayamashita/atom,FIT-CSE2410-A-Bombs/atom,decaffeinate-examples/atom,me-benni/atom,CraZySacX/atom,AdrianVovk/substance-ide,Mokolea/atom,FIT-CSE2410-A-Bombs/atom,Mokolea/atom,andrewleverette/atom,FIT-CSE2410-A-Bombs/atom,stinsonga/atom,decaffeinate-examples/atom,AlexxNica/atom,andrewleverette/atom,t9md/atom,sotayamashita/atom,CraZySacX/atom,tjkr/atom,ardeshirj/atom,Arcanemagus/atom,atom/atom,decaffeinate-examples/atom,liuderchi/atom,xream/atom,Arcanemagus/atom,CraZySacX/atom,brettle/atom,rlugojr/atom,andrewleverette/atom,AlexxNica/atom,decaffeinate-examples/atom,rlugojr/atom,liuderchi/atom,AlexxNica/atom,Mokolea/atom,me-benni/atom,rlugojr/atom,PKRoma/atom,tjkr/atom,kevinrenaers/atom,liuderchi/atom,brettle/atom,bsmr-x-script/atom,liuderchi/atom,sotayamashita/atom,stinsonga/atom,stinsonga/atom,tjkr/atom,atom/atom,stinsonga/atom,PKRoma/atom,AdrianVovk/substance-ide,Arcanemagus/atom,t9md/atom