Updates for online tutorial v6

This PR contains updated files for the SCM v6 online tutorial.

Updates to .F90 and .meta files. (Remove _init and _finalize routines. Remove "optional" arguments from metadata files. Changes to "standard_names")
Update plot configuration using new supported SDFs and run directory locations (output from scm has moved from scm/bin to scm/run). All of the changes in this PR are isolated to the tutorial_files directory, except for a change to the plot configuration in the main repo, scm/etc/scripts/plot_configs/twpice_all_suites.ini. This is used in the online tutorial exercise 1, "run the SCM".
New SDFs used in the online tutorial. From GFS_v15p2 -> GFS_v16 and RRFS_v1alpha -> RRFS_v1beta.
The online tutorial relies on the multirun functionality to run the SCM for all supported SDFs using the twpice case. How to do this has recently changed. There is a new configuration file in tutorial_files/config/ needed by run_scm.py to create these cases for the v6 tutorial.
Update default namelist and tracer information for each supported SDF. Information defined in scm/src/default_namelists.py and scm/src/default_tracers.py for the v5 tutorial is now handled in scm/src/suite_info.py.

NCAR / ccpp-scm