Don’t cancel MoveAdjacentTo / MoveWithinRange when target becomes invalid.

Move to the last known position instead.  Fixes #5968.
Calculate a new path (and possibly new target cell) if the original path is blocked.
Fix a typo.
Merge pull request #5977 from pchote/oi-keep-moving

Don’t cancel MoveAdjacentTo / MoveWithinRange when target becomes invalid
Make momentarily removal from world in Actor.ChangeOwner conditional on whether it is in the world
Make Actor.ChangeOwner behavior more controllable by moving/using World.AddFrameEndTask outside
Make Cargo and ProximityCapturable use Actor.ChangeOwner
Merge OnCapture calling into Actor.ChangeOwner
Split OnCapture into {Before,After}Capture and added Lua events.
Add INotifyHostCapture and use it to move Actor.ChangeOwner from Cargo & OreRefinery to Passenger & Harvester
AUTHORS
Add OpenRA.Primitives.MbaqFunc<T>