Adds getAdditionalPropertiesIsAnyType/setAdditionalPropertiesIsAnyType to java schema classes
This is needed if one is generating classes for object schemas.
By default object schema includes additionalProperties = AnyType, so if this boolean is False, then one needs to generate a custom class for the object schema.
Tests added of X.getAdditionalPropertiesIsAnyType for:

• CodegenModel
• CodegenProperty
• CodegenParameter
• CodegenResponse

This will be used in:
#8325
And will probably want to be used in go-experimental @wing328
We may want to replace isAdditionalPropertiesTrue with getAdditionalPropertiesIsAnyType @wing328
getAdditionalPropertiesIsAnyType applies to all schema models and is also set to true if the user manually defined an additionalProperties in their spec and its value is any type schema.

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