Fixes#1385
## Changes
Supports multiple crawler 'channels' which can be configured to
different browsertrix-crawler versions
- Replaces `crawler_image` in helm chart with `crawler_channels` array
similar to how storages are handled
- The `default` crawler channel must always be provided and specifies
the default crawler image
- Adds backend `/orgs/{oid}/crawlconfigs/crawler-channels` API endpoint
to fetch information about available crawler versions (name, image, and
label) and test
- Adds crawler channel select to workflow creation/edit screens and
profile creation dialog, and updates related API endpoints and
configmaps accordingly. The select dropdown is shown only if more than
one channel is configured.
- Adds `crawlerChannel` to workflow and crawl details.
- Add `image` to crawler image, used to display actual image used as
part of the crawl.
- Modifies `crawler_crawl_id` backend test fixture to use `test` crawler
version to ensure crawler versions other than latest work
- Adds migration to add `crawlerChannel` set to `default` to existing
workflow and profile objects and workflow configmaps
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Co-authored-by: Ilya Kreymer <ikreymer@gmail.com>
Co-authored-by: Henry Wilkinson <henry@wilkinson.graphics>
