Split up the particle advection/streamline test

The test for particle advection filters was one large test that tested 3 versions --- advection, streamlines, and pathlines --- with each tested for a variety of conditions including asynchronous communication, number of blocks, ghost cells, etc. This was causing the test to take a while and sometimes time out. (It would also sometimes seg fault, which I hope is related.) To attempt to fix this problem, break up this test into pieces so that each piece takes a shorter amount of time.

Because these tests share most of their implementation (which is why they were grouped together in the first place) the common code is placed in a source file of shared implementation. To support this I also added a way to mark a source file to vtkm_unit_tests as a source file that does not contain its own test. Normally you would just compile all of the tests together, select each with command line arguments, and use duplicate add_tests for each argument. But that is not how vtkm_unit_tests works, and it would be too hard to make that change.