Add Verbose Flag

[whannah1]

Zeshaun and I were talking about reducing the amount of output while runnin the diagnostics. Here's an example of the output for a random variable:

Selected region: global
no domain selector
Variable: PRECT
Selected region: global
(128,) (72,)
Metrics saved in: results_ACME_ZM_CTL_ne30_00/lat_lon/MERRA2/MERRA2-PRECT-ANN-global.json
Plot saved in: results_ACME_ZM_CTL_ne30_00/lat_lon/CERES-EBAF-TOA-v2.8/ceres_ebaf_toa_v2.8-FLUTC-JJA-global.png
Starting to run ACME Diagnostics.
test file: /lustre/atlas/proj-shared/cli115/hannah6/ACME/ACME_ZM_CTL_ne30_00/climo_rgr/ACME_ZM_CTL_ne30_00_ANN_200012_200211_climo_fv128x256_aave.nc
reference file: /ccs/proj/cli115/acme_diags_data/obs_for_acme_diags/ceres_ebaf_toa_v2.8_ANN_200101_201612_climo.nc

Out of those lines, I only really care about the variable name and the line with "Plot saved in...". So I propose adding a "verbose" variable that defaults to "False" so we don't have to deal with so much output.