[Databases support] Implement model generator

[rszamszur]

• I have searched the issues of this repo and believe that this is not a duplicate.

Feature Request

Add base implementation for model generator (similar to Rails):
fastapi-mvc generate model Article title:str body:str

This would create:

• a file article.py under package_name.app.models submodule
• a unit test file
• probably a DB migration?

Generated model should inherit from application model base class (also needs to be implemented), which for now won't do much, but in future can have methods for database CRUD, like in Rails you would have:

• Article.new(...)
• Article.update(..)
• and so on

Or any other abstract logic implementations.

This will probably be based on tiangolo/sqlmodel

At least that's the idea. This issue would still require some further research and clarification.