Add pattern matching module for querying Model

[mrkickling]

• We want to be able to query for 'patterns' in AttackGraph, LanguageGraph and Model (this issue is for Model)
• It should be possible to query for a pattern, this means to find a 'chain' of assets with certain properties and associations
• Example of pattern: "Find the chain starting with an asset of type X connected through an association of type Y to a chain of assets ending up in an asset of type Z with property P" -> should return the assets (?)

We might also want to be able to combine patterns from different types of graphs (e.g. Auth->FullAccess in AttackGraph where the asset in the Model is connected to somethingsomething). Keep this in mind during design.

For this issue:

• Create patterns module for Model
• Make it possible to query the Model with a pattern and return matching assets (regex like)
• Tests