Graph database integration

[noboruma]

Is your feature request related to a problem? Please describe.
Today we compute the Graph data in-memory via scope.
This comes with a couple of drawbacks:

• Pain point 1: Backend service cannot be scaled properly
• Pain point 2: The data representation of the graph is not easily accessible outside our code base

Describe the proposed solution
We are proposing to replace scope's in-memory graph representation with neo4j.
With neo4j, we can scale up to at least 10k nodes, where previously we were limited to 1k nodes.
See the https://github.com/deepfence/ThreatMapper/tree/neo4j branch for more details.

Alongside the graph representation change, we will use that opportunity to revamp ThreatMapper code. Our plan is to:

• Rework our backend architecture to bring in additional performance and scalability

See the architecture below:

Components/Services

• UI/Frontend
• API/Backend
• Agent
• Deployment/YAMLs
• CI/CD Integration