Setup oppiabot workflow

[jameesjohn]

Overview

1. This PR fixes or fixes part of #[fill_in_number_here].
2. This PR does the following: Sets up oppiabot's GitHub actions check.

Essential Checklist

• The PR title starts with "Fix #bugnum: ", followed by a short, clear summary of the changes. (If this PR fixes part of an issue, prefix the title with "Fix part of #bugnum: ...".)
• The linter/Karma presubmit checks have passed locally on your machine.
• "Allow edits from maintainers" is checked. (See here for instructions on how to enable it.)
  • This lets reviewers restart your CircleCI tests for you.
• The PR is made from a branch that's not called "develop".

PR Pointers

• Oppiabot will notify you when you don't add a PR_CHANGELOG label. If you are unable to do so, please @-mention a code owner (who will be in the Reviewers list), or ask on Gitter.
• For what code owners will expect, see the Code Owner's wiki page.
• Make sure your PR follows conventions in the style guide, otherwise this will lead to review delays
• Never force push. If you do, your PR will be closed.

[oppiabot]

Assigning @kevinlee12 for the first-pass review of this pull request. Thanks!

[ankita240796]

LGTM, Thanks @jameesjohn!

Can you please add screenshots/links of the tests you tried on your repo?

[jameesjohn]

Issue labelled check: jameesjohn/comment-on-pr#29

Issue assigned check: jameesjohn/comment-on-pr#35

[ankita240796]

LGTM!

[jameesjohn]

PTAL @kevinlee12
Thanks

[vinitamurthi]

The PR build is in the build queue, and in an attempt to reduce the pressure, we have moved the lint and backend tests to Github Actions. For quicker test results, can @jameesjohn please merge from develop and push? We have cancelled your build so that it will run quicker when you merge and push

[jameesjohn]

I just did that @vinitamurthi (after getting Sean's mail).

[vinitamurthi]

Oh I think you did it a bit too soon and the code change we wanted in your branch wasn't available :) Now that you have merged again you are good to go (notice that backend and lint tests are not in circle ci anymore)

[jameesjohn]

Yup
Thanks

[kevinlee12]

lgtm!

[jameesjohn]

I'm not sure why frontend tests should be failing here

[kevinlee12]

@jameesjohn can you merge from develop once more?

[jameesjohn]

It's already up to date @kevinlee12

[kevinlee12]

I’ve restarted it, but can you run it locally? If it fails, talk to Nithesh or any one of the core maintainers.

[kevinlee12]

I don't see this impacting the results of other tests, so @ankita240796, you might want to talk with Sean to see if we should just merge this PR.