Generate Sensitivity curve

[Russell-Ryan]

We have "effective area" curves, but these should be converted to inverse sensitivity and distributed to the team. This has several advantages:

1. ensure consistency between the groups in terms of what is included.
2. in flight, we will be given an inverse sensitivity. Therefore there's no reason not to plan accordingly.
3. existing codes (e.g. grizli) are sure to expect an inverse sensitivity.

This requires just taking the effective area curve, including the energy of the photon, factoring out area of primary mirror (recall struts and secondary eclipse some fraction of the primary), and care of the units. This file should be written as a fits BinTable, please see the HST versions to ensure the header and columns are appropriately named (unclear what the in-flight file will look like).