Initialize all the rules from the configuration file

Class [ComparisonMessages](https://github.com/Azure/openapi-diff/blob/master/openapi-diff/src/modeler/AutoRest.Swagger/ComparisonMessages.cs#L3) should be initialized from the json file for all the rules.

- [ ] Initialization from config file
- [ ] Categorization from config file
- [ ] Run tools in context (Azure v/s NonAzure, SDK v/s NonSDK)
- [ ] Initialize the severity from the config file
- [ ] Generate documentation from master list of rules

Start with ComparisonMessages.cs and locate the JSON configuration file used by the project. Trace the current rule initialization, then use the checklist to define completion: configuration-driven initialization, categorization, context-specific tools, severity, and documentation from the master rule list.

索引モデルが issue の本文から書いたものです。