feat: adding pagination to codegen

[alexforsyth]

Issue #, if available:

Description of changes:
Adding Pagination code generation.

Please be kind! This is basically the first time i've touched java code since ?highschool?. Please let me know what to change - im sure i'm missing lots of obvious stuff.

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[alexforsyth]

For reference: When this is run on the test (ListCities) this will generate this paginator file:

import { Weather } from "../Weather";
import { WeatherClient } from "../WeatherClient";
import {
  ListCitiesCommand,
  ListCitiesCommandInput,
  ListCitiesCommandOutput,
} from "../commands/ListCitiesCommand";
import { WeatherPaginationConfiguration } from "./Interfaces";
import { Paginator } from "@aws-sdk/types";

const makePagedClientRequest = async (client: WeatherClient, input: ListCitiesCommandInput, ...additionalArguments: any): Promise<ListCitiesCommandOutput> => {
  // @ts-ignore
  return await client.send(new ListCitiesCommand(input, ...additionalArguments));
}
const makePagedRequest = async (client: Weather, input: ListCitiesCommandInput, ...additionalArguments: any): Promise<ListCitiesCommandOutput> => {
  // @ts-ignore
  return await client.listCities(input, ...additionalArguments);
}
export async function* listCitiesPaginate(config: WeatherPaginationConfiguration, input: ListCitiesCommandInput, ...additionalArguments: any): Paginator<ListCitiesCommandOutput>{
  let token = config.startingToken || '';
  let hasNext = true;
  let page:ListCitiesCommandOutput;
  while (hasNext) {
    input["nextToken"] = token;
    input["pageSize"] = config.pageSize;
    if(config.client instanceof Weather) {
      page = await makePagedRequest(config.client, input, ...additionalArguments);
    }
    else if (config.client instanceof WeatherClient) {
       page = await makePagedClientRequest(config.client, input, ...additionalArguments);
    }
    else {
       throw new Error("Invalid client, expected Weather | WeatherClient");
    }
    yield page;
    token = page["nextToken"];
    hasNext = !!(token);
  }
  return undefined;
}

[alexforsyth]

This will also generate this interface:

import { Weather } from "../Weather";
import { WeatherClient } from "../WeatherClient";
import { PaginationConfiguration } from "@aws-sdk/types";

export interface WeatherPaginationConfiguration extends PaginationConfiguration {
  client: Weather | WeatherClient;
}

[alexforsyth]

To make this work, a customer would need to write:

(async () => {
    const paginatorConfiguration: WeatherPaginationConfiguration = {
        client: new Weather({...})
    };
    const listCitiesInput: ListCitiesCommandInput = {...};
    const paginator = listCitiesPaginate(paginatorConfiguration, listCitiesInput);

    for await (const page of paginator) {
        console.log(page);
        // do stuff with the page
    }
})();