JOSM #21572 - Add "was" search keyword for searching in object history

[Woazboat]

Added the was keyword to the search function to allow matching objects based on their previous states. I.e. was <expr> matches an object if <expr> matches any previous version of the object.

Example:

• was building=* to search for all objects that either currently have a building=* tag or have had this tag at any point in their history.
• was building=* -building=* to search for all objects that previously had a building=* tag which was removed at some point.

[Woazboat]

https://josm.openstreetmap.de/ticket/21572