Slow performance of insert_many when creating new timetable

[lukeskywalker22]

Problem

Calling campus.api.timetable.new() with full timetable data results in a timeout (60 s).

Verification: Calling campus.api.timetable.new() with a smaller json file does not produce the timeout observed with the full timetable json file, likely a performance issue on the backend server.

Resolution

Implement optimised insert_many() method for postgres/mongodb backends, optionally for sqlite/memory backends (used for testing only)

Tasks

• Implement SQLiteTable.insert_many()
• Implement MemoryCollection.insert_many()