Change part serial position to unlocated

@hmccabe Current Position of the serial part is connected to changes in different modules and it cannot be manually updated, but changes carried out in other areas would update the Current Position accordingly.

Current Position is updated to Unlocated when the Operational Status of the serial part is changed to Scrapped, Planned for Operations and Renamed (as per the help text).

So if it is required to update the Current Position to Unlocated, above three options can be tried out.

For an example when a part is renamed (eg: change of the serial no) which is the simplest, the Operational Status is changed to Renamed and then Current Position is changed to Unlocated.

Hope this helps !