Suggestions for 'Projects'

[ots22]

See #475 and #486 that introduce projects

• 'select multiple options' might be prefereable to 'add zero or more models' (all with a single dropdown selector)

  • cf. 'suitable tasks' on new-datasource

• Create scivision projects catalog and add first entry for testing purposes #475 introduced ModelEnum whose values refer to a model name (key) in models.json - somewhat unusual use of an enum

  • it is true that the tasks/tags enums are also generated dynamically, but the intention is for there to be a small, fixed number of these

• Consequence of above point: the project json schema contains hard-coded model/datasource names, rather than indicating the foreign key relationship. This isn't critical for our current use case, but would be preferable to encode this directly