Change to datamodel-code-generator and pydantic 2

[jimisola]

Summary

Our current solution of custom classes, parsing and validation of reqstool yaml files is not core business logic.
It would be nice if we can use a library/tool for that in order to just focus on the business logic.

Blocked by:

• Code not generated for patternProperties in JSON Schemas koxudaxi/datamodel-code-generator#1851

Proposal

Change to datamodel-code-generator and pydantic 2

We can then generate pydantic 2 datamodels from JSON Schemas using datamodel-code-generator.
Using pydantic we can then populate are datamodels by having pydantic parse and validate the data.

It could be helpful to use dynaconf as a preprocessor to get support environment variables and dotenv, integration with HashiCorp Vault and Redis etc.

Pydantic has support for environment variables but both options have to be investigated.