Add opdtable as an optional paramater to monthly_trending_plot()

[kulpster85]

This feature request is to allow external utilities (alternative to MAST Query) to utilize the monthly trending plot to pass in the opdtable as a parameter to monthly_trending_plot.

def monthly_trending_plot(year, month, verbose=True, instrument='NIRCam', filter='F200W', vmax=200):

This feature request would allow the opdtable to be provided which would contain the OPD file paths to circumvent calls under the hood that use the Mast Query API within WebbPSF:

webbpsf/trending.py:814 inst.load_wss_opd(opd_fn, verbose=verbose) webbpsf/webbpsf_core.py:1446 filename = webbpsf.mast_wss.mast_retrieve_opd(filename, output_path = output_path, verbose=verbose)