Ensure all supported file formats are printable

[eloquence]

The MIME types intended to be supported by the SecureDrop Workstation are documented in this spreadsheet.

For the beta, we should ensure that all file formats with the classification "Should be printable - yes (must)" are in fact printable. This may entail conversion to a file format we can process (e.g., PDF or PS) by a helper utility, which may be influenced by the final choice of front-end in freedomofpress/securedrop-client#2156.

For the beta, we should also return two error types to the client:

• file format not currently supported
• not a printable file format (e.g., video, audio, archives)

[eloquence]

2022-08-10 review:

• Closing as stale
• Disabling print action for unsupported formats is tracked in Disable "Print" when file format is not conducive to printing securedrop-client#918
• Specific file format / file issues are tracked in relevant component repos like securedrop-export; we also have other redundant issues like [securedrop-export] [test + docs] Which files do we support? securedrop-client#1728