Add new Loaders page to UI
To allow not just Pipelines and Extractors to be managed through the UI, we should add a new Loaders page modeled after the new and improved Extractors page.
We already had such a page before, but it was removed in !1359 (merged). We should be able to recover the
Loaders component from that MR and start from there, although we may be better off starting with the Extractors page. We'll likely also want to use the
LoaderSettingsModal component, which still exists in the codebase but is not currently used.
We should also not forget to:
- Add a "Manage loaders" link to the "Add pipeline" modal on the Pipelines page: #2068 (closed)