PDE-4677 fix(core): RawHttpResponse method types

[eliangcs]

Fixes #734, where the response of z.request({ raw: true }) doesn't have correct method typings for TypeScript.

Example TypeScript Code

import { Bundle, ZObject } from 'zapier-platform-core';

const getJson = async (z: ZObject): Promise<object> => {
  const response = await z.request({
    url: 'https://httpbin.zapier-tooling.com/get',
    raw: true,
  });
  return response.json();
};

const getBuffer = async (z: ZObject): Promise<Buffer> => {
  const response = await z.request({
    url: 'https://httpbin.zapier-tooling.com/image/png',
    raw: true,
  });
  return response.buffer();
};

const getText = async (z: ZObject): Promise<string> => {
  const response = await z.request({
    url: 'https://httpbin.zapier-tooling.com/status/418',
    raw: true,
    skipThrowForStatus: true,
  });
  return response.text();
};

const getContent = async (z: ZObject): Promise<Buffer> => {
  const response = await z.request({
    url: 'https://httpbin.zapier-tooling.com/robots.txt',
    raw: true,
  });
  return response.content;
};

Current Behavior

When running the tsc transpiler, response.buffer(), response.json(), and response.text() report errors. response.content, on the other hand, should report an error, but passes instead.

Expected Behavior

[eliangcs]

RawHttpResponse.content isn't a valid property and shouldn't be here. When used, it would throw a runtime error.