Quantity Fix for Assigned Usage Quantity having Null

index.view.js:
Introduced a fix that resets Quantity to 1 if the quantity is synced
from the server as null.
Updating Inventory Items for Loaner/External Comparison
Added External Fields to Usage

Usage table now contains externalInventoryLoc and externalWarehouseId to
help with tracking external vs loaner items. Loaner items cannot change
their inventoryLoc, but External items can. So only the
externalInventoryLoc will be changed when updating Inventory Location
for usage items. externalWarehouseId is just an extension of
externalInventoryLoc
Updating Inventory Items for Loaner/External Comparison, Part 2
Updating Inventory Items for Loaner/External Comparison, Part 3

Reference Quantity and External Quantity for Loaner Items and External
Items respectfully.