Do not overwrite custom queryables and collection summaries when automatically updating

[mishaschwartz]

Currently, the PATCH /queryables and PATCH /summaries endpoint will update the queryable and summary data based on the item data currently present in the database. This will overwrite any previous data.

We would like to be able to differentiate automatically generated queryable and summary data from custom data so that these routes only update the automatically generated data. This would allow users to include their own data that won't be overwritten.

For example:

• a user creates summary data (data1) for a given collection
• a user then adds more items to the collection and runs PATCH /summaries which generates additional summary data (data2)
• data2 should be added in addition to data1
• if the user then runs PATCH /summaries at a later date it should overwrite data2 but not data1

See also: #18 (comment)