[protobuf-schema] Support oneOf and AnyOf

[lucy66hw]

ref #20472
Support oneOf and anyOf.
Expecting protobuf message as following:
spec:

 Animal:
     anyOf:
       - $ref: '#/components/schemas/Cat'
       - $ref: "#/components/schemas/Dog"
       

protobuf:

 Message Animal {
   Cat cat = 1;
   Dog dog = 2;
 }

spec:

 Animal:
     oneOf:
       - $ref: '#/components/schemas/Cat'
       - $ref: "#/components/schemas/Dog"

protobuf:

   message Animal {
         oneof animal {
           Cat cat = 1;
           Dog dog = 2;
         }
 }

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[wing328]

thanks for the PR

what about updating modules/openapi-generator/src/test/resources/3_0/protobuf/petstore.yaml with some test schemas for oneOf and anyOf to cover the change?

[lucy66hw]

@wing328 Thanks for reviewing.
Updated modules/openapi-generator/src/test/resources/3_0/protobuf/petstore.yaml by adding oneOf and anyOf schema for testing.

[wing328]

thanks for adding more tests.

let's give it a try