fix: generate sourcemaps for expo projects

[andreybutov]

Status

READY/WIP/HOLD

Description

This is an update to the honeybadger-upload-sourcemaps.sh script that includes the proper way of generating and uploading sourcemaps for Expo projects. The README.md doc was updated to reflect the new --expo param.

Steps to Test or Reproduce

Outline the steps to test or reproduce the PR here.

> git pull --prune
> git checkout <branch>
> grunt jasmine

1. Run npx honeybadger-upload-sourcemaps --apiKey <api_key> --revision --expo to generate iOS and Android sourcemaps in an Expo project.
2. Send a test crash
3. Check to make sure the sourcemaps are applied