Create function for aperture photometry

[evavagiakis]

Create a function to apply aperture photometry to a 2D temperature submap submap and return the average value within a disk of radius R, the average value within an annulus of inner radius R and outer radius sqrt(2)*R, and the signal, -. This is described in https://arxiv.org/pdf/2101.08373.pdf sec IIIA and some example code to reference can be found here: https://github.com/evavagiakis/tSZ_codes_V21/blob/main/tSZ_stacking_V20.py

[elaine-ran]

This issue was fixed by adding the aperture photometry function to make_sz_cluster.py (get_tSZ_signal).