chore: extend FileTypes enum

[jessicamcinchak]

This PR introduces a breaking change - but one that we think will be a much more meaningful and scalable naming convention going forward for communicating about uploaded documents, drawings, and the types of information contained in them.

Changes:

• Allowed file type enum values are updated based on discussions here: https://docs.google.com/spreadsheets/d/1ePihRD37-2071Wq6t2Y7QtBt7juySWuVP6SAF6T-0vo/edit#gid=842355497
• Existing example payloads are updated

[jessicamcinchak]

Update document types and add secondary schema for "files" when provided as data (eg Heritage Statements)

[DafyddLlyr]

Small PR but a lot of work behind the scenes!

I've started looking at the file rules changes discussed earlier this week - might make sense to hold off a little while here and publish one set of breaking changes once I've caught up with the BOPS team?