Use webpack `script-loader` to load sourcegraph bundle
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## Description
The following discussion from !16556 should be addressed:
- [ ] @pslaughter started a [discussion](https://gitlab.com/gitlab-org/gitlab/merge_requests/16556#note_233448723): (+1 comment)
> **suggestion:** It looks like we can actually use Webpack's `script-loader` instead of manually creating a `<script>`. Here's a patch for this:
>
> [0001-Use-script-loader-instead-of-manually-creating-scrip.patch](/uploads/6035d57d92fff21bf2bbcc663df762ec/0001-Use-script-loader-instead-of-manually-creating-scrip.patch)
>
> I don't think we need to address it in this MR, but I'd like to create a follow-up issue for it.
issue