Pydantic improvements

[ZergLev]

Description:

• TLDR: All classes in /chatsky/pipeline/ are rewritten in Pydantic, some changes to class hierarchy and the classes themselves. Changed tutorials with regards to new class signatures.
• Classes PipelineComponent, Pipeline and ComponentExtraHandler are now subclasses of Pydantic's BaseModel, massively reducing code bloat in their initialization and that of their children (such as Service).
• Also, classes Service, ServiceGroup and Actor are now subclasses of PipelineComponent. No functionality is removed in ServiceGroup. All tutorials and tests pass like before, with a few changes.
• Reasoning for changing class hierarchy: Before this, an instance of Actor would be called from within a Service with a special flag, which seemed like a workaround, and now it can be called directly as an instance of PipelineComponent, instead of heavily relying on the Service class. You could say that this slightly reduces the code's complexity. In fact, it also binds Actor to PipelineComponent, instead of it being independent, making code look more cohesive.
• TypeBuilders have been removed, because Pydantic can already deal with them effectively, giving type hints for IDE like before. Different input types are still handled like before, except nested Service declaration is removed. (Service class doesn't accept Service as it's handler anymore) Same with nested ComponentExtraHandlers.
• For some reason Extra Handlers in Services would work even if the Service itself was turned off via start_condition. That was a bug. Now this condition is checked in PipelineComponent instead. I assume Actor must always have it as True.

Checklist

• Removed from_script() and other redundant methods.
• Changed components into pre-services and post-services throughout tutorials. (at Pipeline initialization)
• Got tests to pass.
• I have performed a self-review of the changes
• Updated Pipeline's API and tutorials

To Consider

• Add more tests if necessary
• Update the remaining API reference / tutorials / guides
• Search for more references to changed entities in the codebase