Add undefined check for location when persisting layout

[bingenito]

Depending on usage there might not be a location and this will cause layout persistence to fail.

https://github.com/Morgan-Stanley/desktopJS/blob/1232b91bb1d82b12198269ef80f994757e344049/packages/desktopjs/src/Default/default.ts#L404

https://github.com/Morgan-Stanley/desktopJS/blob/1232b91bb1d82b12198269ef80f994757e344049/packages/desktopjs-openfin/src/openfin.ts#L678

https://github.com/Morgan-Stanley/desktopJS/blob/9b63eb1943e7adb7d9dc31b2df0ef29f396d64b9/packages/desktopjs-electron/src/electron.ts#L536

[bingenito]

From offline discussions with users, this is only necessary to add in DefaultContainer since it is the base implementation used for custom containers.