Create an image velocimetry "grid creation" tool

Users will need to specify the grid of points where image velocimetry should be performed. At the minimum:

1. Need to define an ROI
2. Specify the resulting vector grid characteristics (this is tricky b/c this grid will change the IA and SA for PIV processing potentially...see note))

#24 (closed) is a precursor issue

Notes: Right now, I am considering the possibility of decoupling the resultant grid from the processing grid by utilizing the image_interpolant in the common_functions. If successful, this approach would eliminate the need to be concerned about PIV IA/SA sizing in this particular issue. The user would only need to specify where they want vectors to be processed.

Ultimately, this issue probably should primarily support ROI creation. The grid stuff can be sorted in a few different ways. One other option is to go ahead and create the image stack at the conclusion of this step.