Allow jobItem and job to have multiple materials

[jackcrane]

We want to be able to assign and charge for multiple materials in a single job item; e.g. in 3d printing for "model and support", or "primary and secondary" materials. Right now, there is a secondaryMaterial reference in the job database model, but it is not otherwise implemented.

Steps/completion status:

• Secondary Material field added to jobItem
• Secondary Material qty field added to job and jobItem
• UI for selecting a secondary material (can just use the existing list of materials accessible from useMaterials(), materials do not need to be sorted into primary and secondary) (should work similar to how a primary material can be selected across an entire job or on a per-job-item basis)
• UI for entering the quantity of the secondary material
• Include secondary material in pricing tables, calculations, and quotes.