Codegen: Define tag using extension property

[joshhunt]

When using @rtk-query/codegen-openapi, we would like to automatically set providesTags and invalidatesTags for endpoints based on a custom OpenAPI extension we've added to our spec on operations.

I know of the existing tag option, but our existing OpenAPI spec uses tags to define much broader set of operations, so instead we would like to define an additional property for tags.

For example, if we have the following spec:

"/pets":
  get:
    operationId: getPets
    responses: ...
    summary: Get a list of all adopted pets
    tags:
      - unrelated-broader-tag
+   x-rtk-provides-tags: pet
  post:
    operationId: adoptPet
    requestBody:
      content: ...
      required: true
      x-originalParamName: body
    responses: ...
    summary: Adopts a new pet
    tags:
      - unrelated-broader-tag
+   x-rtk-invalidates-tags: pet

And I would like to configure @rtk-query/codegen-openapi with something like

const config: ConfigFile = {
  schemaFile: './openapi3.json',
  apiFile: './baseAPI.ts',
  apiImport: 'baseAPI',
  hooks: true,
+ tag: {
+   provides: 'x-rtk-provides-tags',
+   invalidates: 'x-rtk-invalidates-tags',
+ }
};

to generate something like

import { baseAPI as api } from './baseAPI';
const injectedRtkApi = api.injectEndpoints({
  endpoints: (build) => ({
    getPets: build.query<GetPetsApiResponse, GetPetsApiArg>({
      query: () => ({ url: `/pets` }),
+     providesTags: ['pet'],
    }),
    adoptPet: build.mutation<AdoptPetApiResponse, AdoptPetApiArg>({
      query: (queryArg) => ({ url: `/pets`, method: 'POST', body: queryArg }),
+     invalidatesTags: ['pet'],
    }),

If it would be accepted, I would be happy to contribute this in a PR.