Update document types to use RDF Schema

Is your feature request related to a problem? Please describe.
Currently, all our documents are assigned a type, which is a value from the enum docTypes. However, defining shared values like reduces interoperability, which is a core value proposal of our application. The only way for someone to know what the type of a document means is to run it through the PASS application. Other applications won't be able to effectively interpret it.

Describe the solution you'd like
Replace the values in docTypes with urls from schema.org or a similar web ontology. We should be able to find values for driver's license, passport, and bank statement at least.

Additional context
The interoperability standards for Solid are not very strong right now, and they are likely to be revised in the next couple years. However, we can get a good head start on interoperability by making sure that any information written out by PASS does not come from the application itself. Instead, it should come from either:

a) the user
b) a schema library like schema.org

Some recommended libraries:
https://hmis-interop.github.io/
schema.org

Start by locating the docTypes enum and reviewing the schema.org and HMIS Interoperability references linked in the issue. The work is done when driver’s license, passport, and bank statement types use agreed ontology URLs rather than application-defined values, with the chosen mappings documented.