RFE: LOS thread to measure points on map in "world unit

Might already be covered in part by #1866669

A way to get scaled distance measurements using essentially what is now the LOS tool between arbitrary (no grid) points. You would perhaps a property in the tool that would configure units per pixel at a zoom factor of 1.00 and then use the current zoom factor and report the length of the LOS string to the user. I do not use the LOS string much myself right now so I do not know how much of this is already there or how one would adapt to make a new tool.

Note I am presuming one can drop a marker on the map when moving a unit and use the measurement “improved LOS” string to measure the final move distances. There is such a plethora of ways to do this when wheeling is involved that I would hate to try to come up with a universal approach.