Add [GitHubLastCommit] by committer badge

[PaulaBarszcz]

closes #6236

I added the display_timestamp queryParam, with options author and committer, defaulting to author.

const queryParamSchema = Joi.object({
  display_timestamp: Joi.string()
    .valid('author', 'committer')
    .default('author'),
}).required()

...

  async handle({ user, repo, branch }, queryParams) {
    const body = await this.fetch({ user, repo, branch })

    return this.constructor.render({
      commitDate: body[0].commit[queryParams.display_timestamp].date,
    })
  }

I checked a couple of repos (for example https://api.github.com/repos/zero-to-mastery/start-here-guidelines/commits) but I couldn't find an example with a different date for author and committer.

http://localhost:8080/github/last-commit/google/skia/infra/config?display_timestamp=committer

[shields-ci]

	Messages
📖	✨ Thanks for your contribution to Shields, @PaulaBarszcz!

Generated by 🚫 dangerJS against 5b818c0

[chris48s]

Similar to #8543 (comment) I'd make this display_timestamp with options author and committer defaulting to author

[PaulaBarszcz]

Good point, thanks. Updated

[PaulaBarszcz]

Hi @chris48s
For some reason integration tests failed here:

https://github.com/badges/shields/actions/runs/3290599111/jobs/5423657553

[chris48s]

I think the integration test failure is probably related to #8535 / #8538

[pukkandan]

Thanks