- rename 'collections' -> 'collectionIds', adding migration 0014
- only populate 'collections' array with {name, id} pair for get_crawl() / single archived item
path, but not for aggregate/list methods
- remove Crawl.get_crawl(), redundant with BaseCrawl.get_crawl() version
- ensure _files_to_resources returns an empty [] instead of none if empty (matching BaseCrawl.get_crawl() behavior to Crawl.get_crawl())
- tests: update tests to use collectionIds for id list, add 'collections' for {name, id} test
- frontend: change Crawl object to have collectionIds instead of collections
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Co-authored-by: Ilya Kreymer <ikreymer@gmail.com>