ref #20472
Currently, the Protobuf generator in OpenAPI Generator does not correctly handle complex types, such as:

Maps inside oneof
Arrays inside oneof
Arrays inside maps
Maps inside arrays
When compiling the generated Protobuf schema, these cases result in compilation failures due to structural incompatibilities.

This PR introduces a flag wrapComplexType to have preprocessing logic that modifies the OpenAPI Schema before code generation. It achieves this by adding extra schema definitions to ensure that complex types are correctly transformed into compatible Protobuf structures.

Example:

Tag:
      properties:
        id:
          type: integer
          format: int64
        name:
          oneOf:
            - type: string
            - type: array
              items:
                  type: string
            - type: object
              title: map
              additionalProperties:
                type: string

Before:

message TagName {
 
     oneof tag_name {
         string string = 1;
         repeated string string_array = 2;
         map<string, string> map = 3;
     }
 }

with introduced flag wrapComplexType:

message TagName {
     oneof tag_name {
         string string = 1;
         StringArray string_array = 2;
         StringMap map = 3;
     }
 }

message StringArray {
   repeated string string_array = 1;
 }

message StringMap {
   map<string, string> string_map = 1;
 }

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