Support importing Kit Specifications into Drupal

Problem/Motivation

Kit Specifications in Acumatica hold information about stock or non-stock items that are bundles and depend on other items in order to be built. Importing kit information into Drupal can allow applications to use it, for example, to understand which variations are kits, their dependencies and its stock status/quantities.

Proposed resolution

This should be implemented as a submodule so that it is enabled only on applications that need it.

Remaining tasks

See child tasks.

Data model changes

Introduces a new Kit Specification entity when the Acumatica Kit submodule is enabled.