Remove deprecated concept of Consumables Packages

[tbhallett]

We should remove

• the columns in this file: ResourceFile_Consumables_Items_and_Packages.csv as they are not longer being used and could cause confusion. This file is generated by an analysis script, so the change needs to happen at the level of script. We should be careful that the final script produces a ResourceFile that is identical to that currently in master, except for the removal of these columns. This links to PR update generate_consumables_item_codes_and_packages script #1290 This is the context: Editing units of consumable required for each HSI #1298 (comment)
• the functions in HealthSystem and Consumable that use these columns for lookups. (Note that HIV and TB modules still use them, so changes would be needed to make them use the item_codes instead.)

[tbhallett]

Also noting that in PR #1288, I introduced a file that classifies the item_code into diagnostics/medicine/other.

resources/healthsystem/consumables/ResourceFile_Consumables_Item_Designations.csv

We could merge this information into ResourceFile_Consumables_Items_and_Packages.csv so that the definitions are all in one place. (I didn't do this, knowing that this work is on-going).