Filer type in Docassemble

[BryceStevenWilley]

Adds support of the Filer type, an uncommon court code used (and required) in some Texas jurisdictions.

• adds a method to get the types from the EfileProxy endpoint
• adds a default question, with things to fill it in if there aren't any or only one filer_types
• misc addition to the any_filing_interview, to not let you try to make an initial filing when the court won't let you

Corresponding PR is EfileProxy: https://github.com/SuffolkLITLab/EfileProxyServer/pull/158