Add a Proposal table to an OpSim strategy via rubin-sim

[chrisfrohmaier]

The script in this Pull request will add a Proposal table to an OpSim strategy. Tested on strategies from baseline v2.2 to v3.2.
This will enable the user to run the OpSimSummary code to generate an SNANA simib.

Based on script by rhiannonlynne
Updated for rubin-sim by: Chris Frohmaier (c.frohmaier@soton.ac.uk)
!!! You must have the rubin-sim package in your python environment to run this script !!!
This script has been adapted from a legacy code from LSST: add_fbs_proposals.py
The original script can be found here: https://github.com/lsst-sims/legacy_sims_maf/blob/main/bin.src/add_fbs_proposals.py
All changes are performed in-place.

Updates include:

• summaryallprops -> observations (new table name in sqlite database)
• visitExposureTime, rotSkyPos are selected from observations as they are needed later in the script
• lsst.sims.maf is no longer supported, all instances changed to rubin_sim.maf
• camelCase modules in lsst has been changed to underscores in rubin-sim (some modules still are camelCase)

Usage:
(rubin-sim)$ python add_ProposalTable_rubin_sim.py ./baseline_v3.0_10yrs.db

(Change ./baseline_v3.0_10yrs.db to the path of your OpSim of choice)