Optimise rule generation

[AndyRae]

In #675 we moved to serverless generating Mapping Rules. But further work is necessary to support (very) large scan reports, and prepare for greater scale overall.

A loose plan is to move towards orchestrating the serverless functions, with Durable Functions.

There is also:

• additional optimisation to happen in the rules algorithm itself
• technical debt in the existing functions that still use the Django API rather than connect to the DB directly:
• [x] #703
• [ ] Update UploadQueue function to use the DB

Some of this work is exploratory - as durable functions is new to the team.

Tasks

• [x] New (http?) durable function "Orchestrating" CreateConcepts and MappingRules
• [x] Change the CreateConcepts + MappingRules to be able to be orchestrated
• [x] Change the triggering from Django form to point to the new Orchestrator
• [x] Change refresh_mapping_rules make deleting existing rules optional.
• [ ] Memoize the destination tables in _save_mapping_rules
• [ ] Remove unnecessary lookups in _save_mapping_rules
• [x] Explore whether the "dequeuing" is still relevant in durable functions

Lower Priority

• [x] Explore "status" endpoint of durable functions, is this easy for us to implement as a quick way to give the user a status of the mapping? To make the UX less "eerie"

Acceptance Criteria:

• [x] Reusing mapping rules is durable for scale
• [x] Reduce complexity of the mapping rules algo
• [x] Tests pass