Small CLI Refactors needed in a future PR

[evrose54]

Requested Update

Description

This issue was created due to lingering comments on the #444 PR. Since that PR is a dependency of other PRs like #465 and #478 , we are going to wait to make those updates and finish them up in a separate PR once those have been merged. Since none of the comments address actual bugs, this is largely just a refactoring change and is good to wait until we merge the aforementioned PRs.

Checklist for Completion

Add to the following list for all comments that still need addressing.

• Use consistent naming for pkg in CLI Unit tests (evan)
• Address whether or not we want to use .extend(list) rather than += list. Personally I say we keep it as +=
• Address if we want to refactor all_possible_subcommand_combinations for CLI Unit Tests (See Likely need to refactor command_combinations property in CLI Unit Tests #648) (evan & gwyn)
• Consider renaming all_possible_subcommand_combinations to something more accurate. Some include all cases; some are stochastic. (See Likely need to refactor command_combinations property in CLI Unit Tests #648) (evan & gwyn)
• Consider making separate geoips unit / unit-test command rather than geoips test unit-test (not important right now as this functionality has been completely commented out)
• Move GeoipsExecutableCommand:_get_registry_by_interface_and_package to PluginRegistry class (evan)
• Consider refactoring tabulate portions of GeoipsList to reduce some code duplication (gwyn) #745
• Fix formatting of usage when a command is called incorrectly. For example, geoips list prints usage that is poorly formatted. (evan)

All bullets in the list above that don't have a referenced issue are either described in their entirety above or will most likely not be addressed / relevant in the future. For example, the point talking about geoips test unit-test doesn't have an issue as that functionality will likely be removed.

[evrose54]

A larger change (I'll create another issue later) will be implementing logging within the CLI. See Jeremy's comment at https://github.com/NRLMMD-GEOIPS/geoips/pull/444/files#r1592810697