Adds memoization and deserialization through 2 or more discriminators

[spacether]

Adds memoization with the decorator cached_property and deserialization through 2 or more discriminators in python-experimental
Memoization should decrease the deserialization time through complex schemas
The discriminator logic picking a different model to instantiate has been moved to the __new__ method.

• tests have been added demonstrating the discriminator deserialization through 2 discriminators

@ethan92429 this may solve the problem you were having where deserialization takes a while

This PR along these:

• [MERGED] Improve composed schema discriminator map
• [IN REVIEW] Use the ancestor discriminator dict if the key/value pair is not found in the current discriminator

Should resolve #4912

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@sebastien-rosset

This PR: #5809 also touches python-experimental discriminator code and is in review

[sebastien-rosset]

Memoization should increase the deserialization time through complexschemas

Did you mean "decrease"?

[spacether]

@sebastien-rosset any tips on how to get the go-experimental code working?
I am seeing these errors in CI:
https://circleci.com/gh/OpenAPITools/openapi-generator/15047#config/containers/1
But those interfaces are not required in python-experimental because we iterate over:

{{#requiredVars}}
            '{{name}}': ({{{dataType}}},),  # noqa: E501
{{/requiredVars}}
{{#optionalVars}}
            '{{name}}': ({{{dataType}}},),  # noqa: E501
{{/optionalVars}}

in the composed models Shape/Triangle/Quadrilateral

The go-experimental template is assuming that oneOf child models contain the full interfaces at the composed model level.
So model_shape.go is assuming that model_triangle.go implements the GetShapeType interface.
In python we implement these interfaces with the {{#requiredVars}}.
How should I move forward here?

• Separate off the spec for python-experimental only?

[spacether]

Adding ShapeInterface to Triangle and Quadrilateral is not possible because when we make that change, the codegenModel then drops the oneOf schemas due to this bug: #6143
so I will make a new python-experimental document for our v3 samples.

[wing328]

@spacether thanks for the PR, which has been included in the v4.3.1 release: https://twitter.com/oas_generator/status/1258057660974329861