Add New OD Algorithm: OD Matrix from Layers as Routes

[spatialthoughts]

Thanks for the great work and for providing many different options of OD matrix calculations. One common request I get is to have the OD matrix display the actual routes on the network instead of a straight line. It would be helpful to have another algorithm that can set the geometry of the resulting OD pairs as routes on the network.

[root676]

Thanks for raising this issue @spatialthoughts, I have gotten this request too. I think it would be a useful algorithm. I don't know if I have time to implement this soon because I am thinking about porting QNEAT3 entirely to QGIS core...