Bulk aerosol model (trop_bam) is broken and untested

It appears as though the bulk aerosol model (`-chem trop_bam` option) has been left in the dust, and will no longer build and run. I discovered this while trying to add some test mods to exercise the bulk aerosol-specific section of the aerosol optical properties code that I need to refactor. I spent a little bit of time trying to revive the capability, and with a few mods I can get it to build, but keep running into more and more run-time problems the further I get into it. So, flagging this here. Since this code is unused and untested, we should consider either a) spending some time getting it running again and adding tests for it, or b) removing it altogether since it's currently broken and will likely remain broken.

Start with the `-chem trop_bam` option and the bulk aerosol-specific section of the aerosol optical properties code. Try building and running that configuration to identify the reported failures. Done means either restoring a working, tested bulk aerosol model or removing the broken, unused capability, depending on the project decision.

Written by the indexing model from the issue text.