Python's optparse does not support subcommands, but argparse/click does. To enable doing that, we need to migrate.

• Look into click and whether that would be a better option.
• Define new resmoke syntax with argparse. There are differences between how optparse/argparse work, so the syntax will have to change.
• Add infrastructure for resmoke to run subcommands, with emphasis on extensibility for the future
• Attempt to keep old resmoke syntax (and eventually deprecate). This might not be possible. If not, look into having a legacy flag, or at least print nice error messages to make it easy to figure out the new syntax.
• Update usages of resmoke in the system.
• Update documentation and do engineer outreach to ensure users are aware of the change