Inspiral Extrinsics Feature Branch

This branch finalizes the work that Javed started by exposing angle parameters that control the resolution of the so called "dt / dphi" distributions.

1. Users / developers have access to change the healpix resolution for the sky (with the NSIDE parameter) and the resolution for inclination and polarization.
2. Although APIs and file formats change, this merge should be self consistent and it leaves in place the default resolution used before
3. This merge is necessary to explore tweaking resolution to save on RAM for KAGRA analysis

Additionally, this merge updates some of the DAG tools to support singularity, fixes a few python3 bugs that crept in, and adds documentation to show users how to generate new distribution files.

Lastly, since the distribution files in LFS had to be updated anyway, I took the liberty to update them to the O4 projected sensitivities. The new documentation page shows the exact procedure and relevant DCC files.

Have fun,

Chad