fix(GuildMemberManager): options.roles on 'prune'

[izexi]

Since 257371d was merged, it allowed an array of values to be passed through a query's value (as explained here). f1194af did not accommodate for these changes that were committed beforehand to make include_roles=foo&include_roles=bar possible.

As of discord/discord-api-docs@b9edace#diff-c4e1390fca89ecc96b01a093f988fa1cR720 Discord now accepts a "comma-delimited array of snowflakes"... but the old key=value&key=value still works (and is even being used in the client). This PR changes the prune method to pass comma-delimited array of role IDs for options.roles since that is what is currently documented. The code within the APIRequest class hasn't been changed for more compatibility (incase Discord decides to add or change another query that accepts the key=value&key=value format). compute_prune_count is also excluded from the GET request for the prune in this PR, since that isn't being used.

Fixes #4834

Here's a snippet of how I tested these changes

import { once } from 'events';
import { Client } from 'discord.js';
import { TEST_GUILD_ID, TEST_ROLE_IDS, TOKEN } from './constants';

const client = new Client();
// verified through the client
const EXPECTED_NUMBER = 6;

client.login(TOKEN);

test('GuildMemberManager#prune() with options.roles', async () => {
  await once(client, 'ready');

  const { members } = client.guilds.cache.get(TEST_GUILD_ID);

  // GET
  expect(
    members.prune({
      days: 30,
      roles: TEST_ROLE_IDS,
      dry: true,
    })
  ).resolves.toBe(EXPECTED_NUMBER);

  // POST
  expect(
    members.prune({
      days: 30,
      roles: TEST_ROLE_IDS,
    })
  ).resolves.toBe(EXPECTED_NUMBER);
});

Status

• Code changes have been tested against the Discord API, or there are no code changes
• I know how to update typings and have done so, or typings don't need updating

Semantic versioning classification:

• This PR changes the library's interface (methods or parameters added)
  • This PR includes breaking changes (methods removed or renamed, parameters moved or removed)
• This PR only includes non-code changes, like changes to documentation, README, etc.