Add ability to change file and rerun points via service

[andyblarblar]

To further expand this nodes usefullness,I propose the addition of a service interface that allows for changing the filepath of the readable file, and another (or the same?) that performs the waypoint following on command, rather than on IPP publish like now.

This implimentation should be pretty easy, just make one service change the filepath feild, and another call get waypoints followed by publish waypoints. The only thing to keep in mind is cancelling an already running waypoint follow action if the user calls a rerun while a previous run is still ongoing.

[girvenavery2022]

This sounds like a good addition to this package. like you have said, you just have to be careful to not cancel an already running waypoint follow action by asking for a rerun too early. This is something I am going to have to implement on the rviz plugin I am developing as well.