This PR fixes #21079. This PR added one more config option isLibrary to FastAPI generator, which is defaulted to false to remain backwards compatible. In library mode, the docker and compose files are not generated and the security API functions use abstract base class to delegate security functionalities. On top of that, this PR also includes parent class ABC to all the base API classes in library mode to ensure all the implementing child classes must implement all the defined methods from the base class.

cc: @multani @fa0311 @krjakbrjak @tomplus @cbornet Can you please look into the PR and if everything is alright, merge this?

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