Updates needed for prescribed MAM5 stratospheric aerosols

[fvitt]

What is the feature/what would you like to discuss?

Update the prescribed_strataero module to consider the 5th mode of MAM5 aerosols.

In addition to new prescribed stratospheric aerosol files, updated radiative physprops files will need to be provided, which will be referenced in namelist settings.

Is there anyone in particular you want to be part of this conversation?

@tilmes

Will this change (regression test) answers?

Yes

Will you be implementing this enhancement yourself?

Yes